diff --git a/README.v2.md b/README.v2.md
index 55d867586..8049d1020 100644
--- a/README.v2.md
+++ b/README.v2.md
@@ -532,7 +532,7 @@ def get_user(user_id: str) -> UserProfile:
 
 # Classes WITHOUT type hints cannot be used for structured output
 class UntypedConfig:
-    def __init__(self, setting1, setting2):  # type: ignore[reportMissingParameterType]
+    def __init__(self, setting1, setting2):  # type: ignore[reportMissingParameterType]  # noqa: ANN001
         self.setting1 = setting1
         self.setting2 = setting2
 
@@ -744,7 +744,7 @@ server_params = StdioServerParameters(
 )
 
 
-async def run():
+async def run() -> None:
     """Run the completion client example."""
     async with stdio_client(server_params) as (read, write):
         async with ClientSession(read, write) as session:
@@ -795,7 +795,7 @@ async def run():
                 print(f"Completions for 'style' argument: {result.completion.values}")
 
 
-def main():
+def main() -> None:
     """Entry point for the completion client."""
     asyncio.run(run())
 
@@ -1210,7 +1210,7 @@ def hello(name: str = "World") -> str:
     return f"Hello, {name}!"
 
 
-def main():
+def main() -> None:
     """Entry point for the direct execution server."""
     mcp.run()
 
@@ -1280,6 +1280,7 @@ uvicorn examples.snippets.servers.streamable_starlette_mount:app --reload
 """
 
 import contextlib
+from collections.abc import AsyncIterator
 
 from starlette.applications import Starlette
 from starlette.routing import Mount
@@ -1308,7 +1309,7 @@ def add_two(n: int) -> int:
 
 # Create a combined lifespan to manage both session managers
 @contextlib.asynccontextmanager
-async def lifespan(app: Starlette):
+async def lifespan(app: Starlette) -> AsyncIterator[None]:
     async with contextlib.AsyncExitStack() as stack:
         await stack.enter_async_context(echo_mcp.session_manager.run())
         await stack.enter_async_context(math_mcp.session_manager.run())
@@ -1392,6 +1393,7 @@ Run from the repository root:
 """
 
 import contextlib
+from collections.abc import AsyncIterator
 
 from starlette.applications import Starlette
 from starlette.routing import Mount
@@ -1410,7 +1412,7 @@ def hello() -> str:
 
 # Create a lifespan context manager to run the session manager
 @contextlib.asynccontextmanager
-async def lifespan(app: Starlette):
+async def lifespan(app: Starlette) -> AsyncIterator[None]:
     async with mcp.session_manager.run():
         yield
 
@@ -1439,6 +1441,7 @@ Run from the repository root:
 """
 
 import contextlib
+from collections.abc import AsyncIterator
 
 from starlette.applications import Starlette
 from starlette.routing import Host
@@ -1457,7 +1460,7 @@ def domain_info() -> str:
 
 # Create a lifespan context manager to run the session manager
 @contextlib.asynccontextmanager
-async def lifespan(app: Starlette):
+async def lifespan(app: Starlette) -> AsyncIterator[None]:
     async with mcp.session_manager.run():
         yield
 
@@ -1486,6 +1489,7 @@ Run from the repository root:
 """
 
 import contextlib
+from collections.abc import AsyncIterator
 
 from starlette.applications import Starlette
 from starlette.routing import Mount
@@ -1511,7 +1515,7 @@ def send_message(message: str) -> str:
 
 # Create a combined lifespan to manage both session managers
 @contextlib.asynccontextmanager
-async def lifespan(app: Starlette):
+async def lifespan(app: Starlette) -> AsyncIterator[None]:
     async with contextlib.AsyncExitStack() as stack:
         await stack.enter_async_context(api_mcp.session_manager.run())
         await stack.enter_async_context(chat_mcp.session_manager.run())
@@ -1718,7 +1722,7 @@ server = Server(
 )
 
 
-async def run():
+async def run() -> None:
     """Run the server with lifespan management."""
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
         await server.run(
@@ -1796,7 +1800,7 @@ server = Server(
 )
 
 
-async def run():
+async def run() -> None:
     """Run the basic low-level server."""
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
         await server.run(
@@ -1889,7 +1893,7 @@ server = Server(
 )
 
 
-async def run():
+async def run() -> None:
     """Run the structured output server."""
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
         await server.run(
@@ -1964,7 +1968,7 @@ server = Server(
 )
 
 
-async def run():
+async def run() -> None:
     """Run the server."""
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
         await server.run(
@@ -2127,7 +2131,7 @@ async def handle_sampling_message(
     )
 
 
-async def run():
+async def run() -> None:
     async with stdio_client(server_params) as (read, write):
         async with ClientSession(read, write, sampling_callback=handle_sampling_message) as session:
             # Initialize the connection
@@ -2165,7 +2169,7 @@ async def run():
             print(f"Structured tool result: {result_structured}")
 
 
-def main():
+def main() -> None:
     """Entry point for the client script."""
     asyncio.run(run())
 
@@ -2191,7 +2195,7 @@ from mcp import ClientSession
 from mcp.client.streamable_http import streamable_http_client
 
 
-async def main():
+async def main() -> None:
     # Connect to a streamable HTTP server
     async with streamable_http_client("http://localhost:8000/mcp") as (read_stream, write_stream):
         # Create a session using the client streams
@@ -2235,7 +2239,7 @@ server_params = StdioServerParameters(
 )
 
 
-async def display_tools(session: ClientSession):
+async def display_tools(session: ClientSession) -> None:
     """Display available tools with human-readable names"""
     tools_response = await session.list_tools()
 
@@ -2247,7 +2251,7 @@ async def display_tools(session: ClientSession):
             print(f"   {tool.description}")
 
 
-async def display_resources(session: ClientSession):
+async def display_resources(session: ClientSession) -> None:
     """Display available resources with human-readable names"""
     resources_response = await session.list_resources()
 
@@ -2261,7 +2265,7 @@ async def display_resources(session: ClientSession):
         print(f"Resource Template: {display_name}")
 
 
-async def run():
+async def run() -> None:
     """Run the display utilities example."""
     async with stdio_client(server_params) as (read, write):
         async with ClientSession(read, write) as session:
@@ -2275,7 +2279,7 @@ async def run():
             await display_resources(session)
 
 
-def main():
+def main() -> None:
     """Entry point for the display utilities client."""
     asyncio.run(run())
 
@@ -2354,7 +2358,7 @@ async def handle_callback() -> tuple[str, str | None]:
     return params["code"][0], params.get("state", [None])[0]
 
 
-async def main():
+async def main() -> None:
     """Run the OAuth client example."""
     oauth_auth = OAuthClientProvider(
         server_url="http://localhost:8001",
@@ -2382,7 +2386,7 @@ async def main():
                 print(f"Available resources: {[r.uri for r in resources.resources]}")
 
 
-def run():
+def run() -> None:
     asyncio.run(main())
 
 
diff --git a/examples/mcpserver/memory.py b/examples/mcpserver/memory.py
index fd0bd9362..5a7f6ab4d 100644
--- a/examples/mcpserver/memory.py
+++ b/examples/mcpserver/memory.py
@@ -50,11 +50,17 @@ def cosine_similarity(a: list[float], b: list[float]) -> float:
     return np.dot(a_array, b_array) / (np.linalg.norm(a_array) * np.linalg.norm(b_array))
 
 
+@dataclass
+class Deps:
+    openai: AsyncOpenAI
+    pool: asyncpg.Pool
+
+
 async def do_ai(
     user_prompt: str,
     system_prompt: str,
     result_type: type[T] | Annotated,
-    deps=None,
+    deps: Deps | None = None,
 ) -> T:
     agent = Agent(
         DEFAULT_LLM_MODEL,
@@ -65,14 +71,8 @@ async def do_ai(
     return result.data
 
 
-@dataclass
-class Deps:
-    openai: AsyncOpenAI
-    pool: asyncpg.Pool
-
-
 async def get_db_pool() -> asyncpg.Pool:
-    async def init(conn):
+    async def init(conn: asyncpg.Connection) -> None:
         await conn.execute("CREATE EXTENSION IF NOT EXISTS vector;")
         await register_vector(conn)
 
@@ -90,11 +90,11 @@ class MemoryNode(BaseModel):
     embedding: list[float]
 
     @classmethod
-    async def from_content(cls, content: str, deps: Deps):
+    async def from_content(cls, content: str, deps: Deps) -> Self:
         embedding = await get_embedding(content, deps)
         return cls(content=content, embedding=embedding)
 
-    async def save(self, deps: Deps):
+    async def save(self, deps: Deps) -> None:
         async with deps.pool.acquire() as conn:
             if self.id is None:
                 result = await conn.fetchrow(
@@ -129,7 +129,7 @@ async def save(self, deps: Deps):
                     self.id,
                 )
 
-    async def merge_with(self, other: Self, deps: Deps):
+    async def merge_with(self, other: Self, deps: Deps) -> None:
         self.content = await do_ai(
             f"{self.content}\n\n{other.content}",
             "Combine the following two texts into a single, coherent text.",
@@ -145,7 +145,7 @@ async def merge_with(self, other: Self, deps: Deps):
         if other.id is not None:
             await delete_memory(other.id, deps)
 
-    def get_effective_importance(self):
+    def get_effective_importance(self) -> float:
         return self.importance * (1 + math.log(self.access_count + 1))
 
 
@@ -157,12 +157,12 @@ async def get_embedding(text: str, deps: Deps) -> list[float]:
     return embedding_response.data[0].embedding
 
 
-async def delete_memory(memory_id: int, deps: Deps):
+async def delete_memory(memory_id: int, deps: Deps) -> None:
     async with deps.pool.acquire() as conn:
         await conn.execute("DELETE FROM memories WHERE id = $1", memory_id)
 
 
-async def add_memory(content: str, deps: Deps):
+async def add_memory(content: str, deps: Deps) -> str:
     new_memory = await MemoryNode.from_content(content, deps)
     await new_memory.save(deps)
 
@@ -204,7 +204,7 @@ async def find_similar_memories(embedding: list[float], deps: Deps) -> list[Memo
     return memories
 
 
-async def update_importance(user_embedding: list[float], deps: Deps):
+async def update_importance(user_embedding: list[float], deps: Deps) -> None:
     async with deps.pool.acquire() as conn:
         rows = await conn.fetch("SELECT id, importance, access_count, embedding FROM memories")
         for row in rows:
@@ -228,7 +228,7 @@ async def update_importance(user_embedding: list[float], deps: Deps):
             )
 
 
-async def prune_memories(deps: Deps):
+async def prune_memories(deps: Deps) -> None:
     async with deps.pool.acquire() as conn:
         rows = await conn.fetch(
             """
@@ -265,7 +265,7 @@ async def display_memory_tree(deps: Deps) -> str:
 @mcp.tool()
 async def remember(
     contents: list[str] = Field(description="List of observations or memories to store"),
-):
+) -> str:
     deps = Deps(openai=AsyncOpenAI(), pool=await get_db_pool())
     try:
         return "\n".join(await asyncio.gather(*[add_memory(content, deps) for content in contents]))
@@ -281,7 +281,7 @@ async def read_profile() -> str:
     return profile
 
 
-async def initialize_database():
+async def initialize_database() -> None:
     pool = await asyncpg.create_pool("postgresql://postgres:postgres@localhost:54320/postgres")
     try:
         async with pool.acquire() as conn:
diff --git a/examples/servers/simple-auth/mcp_simple_auth/auth_server.py b/examples/servers/simple-auth/mcp_simple_auth/auth_server.py
index 9d13fffe4..996cbfa44 100644
--- a/examples/servers/simple-auth/mcp_simple_auth/auth_server.py
+++ b/examples/servers/simple-auth/mcp_simple_auth/auth_server.py
@@ -134,7 +134,7 @@ async def introspect_handler(request: Request) -> Response:
     return Starlette(routes=routes)
 
 
-async def run_server(server_settings: AuthServerSettings, auth_settings: SimpleAuthSettings):
+async def run_server(server_settings: AuthServerSettings, auth_settings: SimpleAuthSettings) -> None:
     """Run the Authorization Server."""
     auth_server = create_authorization_server(server_settings, auth_settings)
 
diff --git a/examples/servers/simple-auth/mcp_simple_auth/simple_auth_provider.py b/examples/servers/simple-auth/mcp_simple_auth/simple_auth_provider.py
index 3a3895cc5..9bd6e3c4e 100644
--- a/examples/servers/simple-auth/mcp_simple_auth/simple_auth_provider.py
+++ b/examples/servers/simple-auth/mcp_simple_auth/simple_auth_provider.py
@@ -66,7 +66,7 @@ async def get_client(self, client_id: str) -> OAuthClientInformationFull | None:
         """Get OAuth client information."""
         return self.clients.get(client_id)
 
-    async def register_client(self, client_info: OAuthClientInformationFull):
+    async def register_client(self, client_info: OAuthClientInformationFull) -> None:
         """Register a new OAuth client."""
         if not client_info.client_id:
             raise ValueError("No client_id provided")
diff --git a/examples/servers/structured-output-lowlevel/mcp_structured_output_lowlevel/__main__.py b/examples/servers/structured-output-lowlevel/mcp_structured_output_lowlevel/__main__.py
index 95fb90854..a11b420e4 100644
--- a/examples/servers/structured-output-lowlevel/mcp_structured_output_lowlevel/__main__.py
+++ b/examples/servers/structured-output-lowlevel/mcp_structured_output_lowlevel/__main__.py
@@ -75,7 +75,7 @@ async def handle_call_tool(ctx: ServerRequestContext, params: types.CallToolRequ
 )
 
 
-async def run():
+async def run() -> None:
     """Run the low-level server using stdio transport."""
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
         await server.run(
diff --git a/examples/snippets/clients/completion_client.py b/examples/snippets/clients/completion_client.py
index dc0c1b4f7..9ef10c5d4 100644
--- a/examples/snippets/clients/completion_client.py
+++ b/examples/snippets/clients/completion_client.py
@@ -17,7 +17,7 @@
 )
 
 
-async def run():
+async def run() -> None:
     """Run the completion client example."""
     async with stdio_client(server_params) as (read, write):
         async with ClientSession(read, write) as session:
@@ -68,7 +68,7 @@ async def run():
                 print(f"Completions for 'style' argument: {result.completion.values}")
 
 
-def main():
+def main() -> None:
     """Entry point for the completion client."""
     asyncio.run(run())
 
diff --git a/examples/snippets/clients/display_utilities.py b/examples/snippets/clients/display_utilities.py
index baa2765a8..1a5e966ed 100644
--- a/examples/snippets/clients/display_utilities.py
+++ b/examples/snippets/clients/display_utilities.py
@@ -17,7 +17,7 @@
 )
 
 
-async def display_tools(session: ClientSession):
+async def display_tools(session: ClientSession) -> None:
     """Display available tools with human-readable names"""
     tools_response = await session.list_tools()
 
@@ -29,7 +29,7 @@ async def display_tools(session: ClientSession):
             print(f"   {tool.description}")
 
 
-async def display_resources(session: ClientSession):
+async def display_resources(session: ClientSession) -> None:
     """Display available resources with human-readable names"""
     resources_response = await session.list_resources()
 
@@ -43,7 +43,7 @@ async def display_resources(session: ClientSession):
         print(f"Resource Template: {display_name}")
 
 
-async def run():
+async def run() -> None:
     """Run the display utilities example."""
     async with stdio_client(server_params) as (read, write):
         async with ClientSession(read, write) as session:
@@ -57,7 +57,7 @@ async def run():
             await display_resources(session)
 
 
-def main():
+def main() -> None:
     """Entry point for the display utilities client."""
     asyncio.run(run())
 
diff --git a/examples/snippets/clients/oauth_client.py b/examples/snippets/clients/oauth_client.py
index 3887c5c8c..115a6b6c8 100644
--- a/examples/snippets/clients/oauth_client.py
+++ b/examples/snippets/clients/oauth_client.py
@@ -52,7 +52,7 @@ async def handle_callback() -> tuple[str, str | None]:
     return params["code"][0], params.get("state", [None])[0]
 
 
-async def main():
+async def main() -> None:
     """Run the OAuth client example."""
     oauth_auth = OAuthClientProvider(
         server_url="http://localhost:8001",
@@ -80,7 +80,7 @@ async def main():
                 print(f"Available resources: {[r.uri for r in resources.resources]}")
 
 
-def run():
+def run() -> None:
     asyncio.run(main())
 
 
diff --git a/examples/snippets/clients/parsing_tool_results.py b/examples/snippets/clients/parsing_tool_results.py
index b16640677..945fa9d01 100644
--- a/examples/snippets/clients/parsing_tool_results.py
+++ b/examples/snippets/clients/parsing_tool_results.py
@@ -6,7 +6,7 @@
 from mcp.client.stdio import stdio_client
 
 
-async def parse_tool_results():
+async def parse_tool_results() -> None:
     """Demonstrates how to parse different types of content in CallToolResult."""
     server_params = StdioServerParameters(command="python", args=["path/to/mcp_server.py"])
 
@@ -52,7 +52,7 @@ async def parse_tool_results():
                         print(f"Error: {content.text}")
 
 
-async def main():
+async def main() -> None:
     await parse_tool_results()
 
 
diff --git a/examples/snippets/clients/stdio_client.py b/examples/snippets/clients/stdio_client.py
index c1f85f42a..44c8bd45b 100644
--- a/examples/snippets/clients/stdio_client.py
+++ b/examples/snippets/clients/stdio_client.py
@@ -33,7 +33,7 @@ async def handle_sampling_message(
     )
 
 
-async def run():
+async def run() -> None:
     async with stdio_client(server_params) as (read, write):
         async with ClientSession(read, write, sampling_callback=handle_sampling_message) as session:
             # Initialize the connection
@@ -71,7 +71,7 @@ async def run():
             print(f"Structured tool result: {result_structured}")
 
 
-def main():
+def main() -> None:
     """Entry point for the client script."""
     asyncio.run(run())
 
diff --git a/examples/snippets/clients/streamable_basic.py b/examples/snippets/clients/streamable_basic.py
index 43bb6396c..d64a05bf3 100644
--- a/examples/snippets/clients/streamable_basic.py
+++ b/examples/snippets/clients/streamable_basic.py
@@ -8,7 +8,7 @@
 from mcp.client.streamable_http import streamable_http_client
 
 
-async def main():
+async def main() -> None:
     # Connect to a streamable HTTP server
     async with streamable_http_client("http://localhost:8000/mcp") as (read_stream, write_stream):
         # Create a session using the client streams
diff --git a/examples/snippets/servers/__init__.py b/examples/snippets/servers/__init__.py
index f132f875f..94220c728 100644
--- a/examples/snippets/servers/__init__.py
+++ b/examples/snippets/servers/__init__.py
@@ -12,7 +12,7 @@
 from typing import Literal, cast
 
 
-def run_server():
+def run_server() -> None:
     """Run a server by name with optional transport.
 
     Usage: server <server-name> [transport]
diff --git a/examples/snippets/servers/direct_execution.py b/examples/snippets/servers/direct_execution.py
index acf7151d3..3fed250ef 100644
--- a/examples/snippets/servers/direct_execution.py
+++ b/examples/snippets/servers/direct_execution.py
@@ -18,7 +18,7 @@ def hello(name: str = "World") -> str:
     return f"Hello, {name}!"
 
 
-def main():
+def main() -> None:
     """Entry point for the direct execution server."""
     mcp.run()
 
diff --git a/examples/snippets/servers/lowlevel/basic.py b/examples/snippets/servers/lowlevel/basic.py
index 81f40e994..1981d22b0 100644
--- a/examples/snippets/servers/lowlevel/basic.py
+++ b/examples/snippets/servers/lowlevel/basic.py
@@ -49,7 +49,7 @@ async def handle_get_prompt(ctx: ServerRequestContext, params: types.GetPromptRe
 )
 
 
-async def run():
+async def run() -> None:
     """Run the basic low-level server."""
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
         await server.run(
diff --git a/examples/snippets/servers/lowlevel/direct_call_tool_result.py b/examples/snippets/servers/lowlevel/direct_call_tool_result.py
index 7e8fc4dcb..ba44fac9e 100644
--- a/examples/snippets/servers/lowlevel/direct_call_tool_result.py
+++ b/examples/snippets/servers/lowlevel/direct_call_tool_result.py
@@ -48,7 +48,7 @@ async def handle_call_tool(ctx: ServerRequestContext, params: types.CallToolRequ
 )
 
 
-async def run():
+async def run() -> None:
     """Run the server."""
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
         await server.run(
diff --git a/examples/snippets/servers/lowlevel/lifespan.py b/examples/snippets/servers/lowlevel/lifespan.py
index bcd96c893..d72c93c2f 100644
--- a/examples/snippets/servers/lowlevel/lifespan.py
+++ b/examples/snippets/servers/lowlevel/lifespan.py
@@ -85,7 +85,7 @@ async def handle_call_tool(
 )
 
 
-async def run():
+async def run() -> None:
     """Run the server with lifespan management."""
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
         await server.run(
diff --git a/examples/snippets/servers/lowlevel/structured_output.py b/examples/snippets/servers/lowlevel/structured_output.py
index f93c8875f..71107b792 100644
--- a/examples/snippets/servers/lowlevel/structured_output.py
+++ b/examples/snippets/servers/lowlevel/structured_output.py
@@ -66,7 +66,7 @@ async def handle_call_tool(ctx: ServerRequestContext, params: types.CallToolRequ
 )
 
 
-async def run():
+async def run() -> None:
     """Run the structured output server."""
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
         await server.run(
diff --git a/examples/snippets/servers/streamable_http_basic_mounting.py b/examples/snippets/servers/streamable_http_basic_mounting.py
index 9a53034f1..e1687ce99 100644
--- a/examples/snippets/servers/streamable_http_basic_mounting.py
+++ b/examples/snippets/servers/streamable_http_basic_mounting.py
@@ -5,6 +5,7 @@
 """
 
 import contextlib
+from collections.abc import AsyncIterator
 
 from starlette.applications import Starlette
 from starlette.routing import Mount
@@ -23,7 +24,7 @@ def hello() -> str:
 
 # Create a lifespan context manager to run the session manager
 @contextlib.asynccontextmanager
-async def lifespan(app: Starlette):
+async def lifespan(app: Starlette) -> AsyncIterator[None]:
     async with mcp.session_manager.run():
         yield
 
diff --git a/examples/snippets/servers/streamable_http_host_mounting.py b/examples/snippets/servers/streamable_http_host_mounting.py
index 2a41f74a5..73cbdd54d 100644
--- a/examples/snippets/servers/streamable_http_host_mounting.py
+++ b/examples/snippets/servers/streamable_http_host_mounting.py
@@ -5,6 +5,7 @@
 """
 
 import contextlib
+from collections.abc import AsyncIterator
 
 from starlette.applications import Starlette
 from starlette.routing import Host
@@ -23,7 +24,7 @@ def domain_info() -> str:
 
 # Create a lifespan context manager to run the session manager
 @contextlib.asynccontextmanager
-async def lifespan(app: Starlette):
+async def lifespan(app: Starlette) -> AsyncIterator[None]:
     async with mcp.session_manager.run():
         yield
 
diff --git a/examples/snippets/servers/streamable_http_multiple_servers.py b/examples/snippets/servers/streamable_http_multiple_servers.py
index 71217bdfe..b95e34d22 100644
--- a/examples/snippets/servers/streamable_http_multiple_servers.py
+++ b/examples/snippets/servers/streamable_http_multiple_servers.py
@@ -5,6 +5,7 @@
 """
 
 import contextlib
+from collections.abc import AsyncIterator
 
 from starlette.applications import Starlette
 from starlette.routing import Mount
@@ -30,7 +31,7 @@ def send_message(message: str) -> str:
 
 # Create a combined lifespan to manage both session managers
 @contextlib.asynccontextmanager
-async def lifespan(app: Starlette):
+async def lifespan(app: Starlette) -> AsyncIterator[None]:
     async with contextlib.AsyncExitStack() as stack:
         await stack.enter_async_context(api_mcp.session_manager.run())
         await stack.enter_async_context(chat_mcp.session_manager.run())
diff --git a/examples/snippets/servers/streamable_starlette_mount.py b/examples/snippets/servers/streamable_starlette_mount.py
index eb6f1b809..ae97982ff 100644
--- a/examples/snippets/servers/streamable_starlette_mount.py
+++ b/examples/snippets/servers/streamable_starlette_mount.py
@@ -3,6 +3,7 @@
 """
 
 import contextlib
+from collections.abc import AsyncIterator
 
 from starlette.applications import Starlette
 from starlette.routing import Mount
@@ -31,7 +32,7 @@ def add_two(n: int) -> int:
 
 # Create a combined lifespan to manage both session managers
 @contextlib.asynccontextmanager
-async def lifespan(app: Starlette):
+async def lifespan(app: Starlette) -> AsyncIterator[None]:
     async with contextlib.AsyncExitStack() as stack:
         await stack.enter_async_context(echo_mcp.session_manager.run())
         await stack.enter_async_context(math_mcp.session_manager.run())
diff --git a/examples/snippets/servers/structured_output.py b/examples/snippets/servers/structured_output.py
index bea7b22c1..422d9001c 100644
--- a/examples/snippets/servers/structured_output.py
+++ b/examples/snippets/servers/structured_output.py
@@ -71,7 +71,7 @@ def get_user(user_id: str) -> UserProfile:
 
 # Classes WITHOUT type hints cannot be used for structured output
 class UntypedConfig:
-    def __init__(self, setting1, setting2):  # type: ignore[reportMissingParameterType]
+    def __init__(self, setting1, setting2):  # type: ignore[reportMissingParameterType]  # noqa: ANN001
         self.setting1 = setting1
         self.setting2 = setting2
 
diff --git a/pyproject.toml b/pyproject.toml
index 624ade170..decfdbd31 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -131,6 +131,7 @@ extend-exclude = ["README.md", "README.v2.md"]
 
 [tool.ruff.lint]
 select = [
+    "ANN",    # flake8-annotations
     "C4",     # flake8-comprehensions
     "C90",    # mccabe
     "D212",   # pydocstyle: multi-line docstring summary should start at the first line
@@ -141,7 +142,14 @@ select = [
     "UP",     # pyupgrade
     "TID251", # https://docs.astral.sh/ruff/rules/banned-api/
 ]
-ignore = ["PERF203"]
+ignore = [
+    "ANN204",  # special methods (__init__, __enter__, etc.) have well-known return types
+    "ANN401",  # `Any` is sometimes the right type; pyright strict handles real misuse
+    "PERF203",
+]
+
+[tool.ruff.lint.flake8-annotations]
+allow-star-arg-any = true
 
 [tool.ruff.lint.flake8-tidy-imports.banned-api]
 "pydantic.RootModel".msg = "Use `pydantic.TypeAdapter` instead."
@@ -152,6 +160,7 @@ max-complexity = 24 # Default is 10
 
 [tool.ruff.lint.per-file-ignores]
 "__init__.py" = ["F401"]
+"tests/**" = ["ANN"]
 "tests/server/mcpserver/test_func_metadata.py" = ["E501"]
 "tests/shared/test_progress_notifications.py" = ["PLW0603"]
 
diff --git a/scripts/update_readme_snippets.py b/scripts/update_readme_snippets.py
index 8a534e5cb..707759277 100755
--- a/scripts/update_readme_snippets.py
+++ b/scripts/update_readme_snippets.py
@@ -138,7 +138,7 @@ def update_readme_snippets(readme_path: Path = Path("README.md"), check_mode: bo
         return True
 
 
-def main():
+def main() -> None:
     """Main entry point."""
     parser = argparse.ArgumentParser(description="Update README code snippets from source files")
     parser.add_argument(
diff --git a/src/mcp/cli/cli.py b/src/mcp/cli/cli.py
index 62334a4a2..5419f912b 100644
--- a/src/mcp/cli/cli.py
+++ b/src/mcp/cli/cli.py
@@ -39,7 +39,7 @@
 )
 
 
-def _get_npx_command():
+def _get_npx_command() -> str | None:
     """Get the correct npx command for the current platform."""
     if sys.platform == "win32":
         # Try both npx.cmd and npx.exe on Windows
@@ -116,7 +116,7 @@ def _parse_file_path(file_spec: str) -> tuple[Path, str | None]:
     return file_path, server_object
 
 
-def _import_server(file: Path, server_object: str | None = None):  # pragma: no cover
+def _import_server(file: Path, server_object: str | None = None) -> Any:  # pragma: no cover
     """Import an MCP server from a file.
 
     Args:
@@ -140,7 +140,7 @@ def _import_server(file: Path, server_object: str | None = None):  # pragma: no
     module = importlib.util.module_from_spec(spec)
     spec.loader.exec_module(module)
 
-    def _check_server_object(server_object: Any, object_name: str):
+    def _check_server_object(server_object: Any, object_name: str) -> bool:
         """Helper function to check that the server object is supported
 
         Args:
diff --git a/src/mcp/client/__main__.py b/src/mcp/client/__main__.py
index f3db17906..c2b98d64d 100644
--- a/src/mcp/client/__main__.py
+++ b/src/mcp/client/__main__.py
@@ -36,7 +36,7 @@ async def run_session(
     read_stream: MemoryObjectReceiveStream[SessionMessage | Exception],
     write_stream: MemoryObjectSendStream[SessionMessage],
     client_info: types.Implementation | None = None,
-):
+) -> None:
     async with ClientSession(
         read_stream,
         write_stream,
@@ -48,7 +48,7 @@ async def run_session(
         logger.info("Initialized")
 
 
-async def main(command_or_url: str, args: list[str], env: list[tuple[str, str]]):
+async def main(command_or_url: str, args: list[str], env: list[tuple[str, str]]) -> None:
     env_dict = dict(env)
 
     if urlparse(command_or_url).scheme in ("http", "https"):
@@ -62,7 +62,7 @@ async def main(command_or_url: str, args: list[str], env: list[tuple[str, str]])
             await run_session(*streams)
 
 
-def cli():
+def cli() -> None:
     parser = argparse.ArgumentParser()
     parser.add_argument("command_or_url", help="Command or URL to connect to")
     parser.add_argument("args", nargs="*", help="Additional arguments")
diff --git a/src/mcp/client/auth/extensions/client_credentials.py b/src/mcp/client/auth/extensions/client_credentials.py
index cb6dafb40..d7e9cae49 100644
--- a/src/mcp/client/auth/extensions/client_credentials.py
+++ b/src/mcp/client/auth/extensions/client_credentials.py
@@ -435,7 +435,7 @@ async def _perform_authorization(self) -> httpx.Request:  # pragma: no cover
         else:
             return await super()._perform_authorization()
 
-    def _add_client_authentication_jwt(self, *, token_data: dict[str, Any]):  # pragma: no cover
+    def _add_client_authentication_jwt(self, *, token_data: dict[str, Any]) -> None:  # pragma: no cover
         """Add JWT assertion for client authentication to token endpoint parameters."""
         if not self.jwt_parameters:
             raise OAuthTokenError("Missing JWT parameters for private_key_jwt flow")
diff --git a/src/mcp/client/sse.py b/src/mcp/client/sse.py
index 7b66b5c1b..78d93fb1b 100644
--- a/src/mcp/client/sse.py
+++ b/src/mcp/client/sse.py
@@ -1,5 +1,5 @@
 import logging
-from collections.abc import Callable
+from collections.abc import AsyncGenerator, Callable
 from contextlib import asynccontextmanager
 from typing import Any
 from urllib.parse import parse_qs, urljoin, urlparse
@@ -36,7 +36,9 @@ async def sse_client(
     httpx_client_factory: McpHttpClientFactory = create_mcp_http_client,
     auth: httpx.Auth | None = None,
     on_session_created: Callable[[str], None] | None = None,
-):
+) -> AsyncGenerator[
+    tuple[MemoryObjectReceiveStream[SessionMessage | Exception], MemoryObjectSendStream[SessionMessage]], None
+]:
     """Client transport for SSE.
 
     `sse_read_timeout` determines how long (in seconds) the client will wait for a new
@@ -68,7 +70,7 @@ async def sse_client(
             read_stream_writer, read_stream = anyio.create_memory_object_stream(0)
             write_stream, write_stream_reader = anyio.create_memory_object_stream(0)
 
-            async def sse_reader(task_status: TaskStatus[str] = anyio.TASK_STATUS_IGNORED):
+            async def sse_reader(task_status: TaskStatus[str] = anyio.TASK_STATUS_IGNORED) -> None:
                 try:
                     async for sse in event_source.aiter_sse():  # pragma: no branch
                         logger.debug(f"Received SSE event: {sse.event}")
@@ -121,7 +123,7 @@ async def sse_reader(task_status: TaskStatus[str] = anyio.TASK_STATUS_IGNORED):
                 finally:
                     await read_stream_writer.aclose()
 
-            async def post_writer(endpoint_url: str):
+            async def post_writer(endpoint_url: str) -> None:
                 try:
                     async with write_stream_reader, write_stream:
                         async for session_message in write_stream_reader:
diff --git a/src/mcp/client/stdio.py b/src/mcp/client/stdio.py
index 902dc8576..29c41a700 100644
--- a/src/mcp/client/stdio.py
+++ b/src/mcp/client/stdio.py
@@ -1,6 +1,7 @@
 import logging
 import os
 import sys
+from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
 from pathlib import Path
 from typing import Literal, TextIO
@@ -102,7 +103,11 @@ class StdioServerParameters(BaseModel):
 
 
 @asynccontextmanager
-async def stdio_client(server: StdioServerParameters, errlog: TextIO = sys.stderr):
+async def stdio_client(
+    server: StdioServerParameters, errlog: TextIO = sys.stderr
+) -> AsyncGenerator[
+    tuple[MemoryObjectReceiveStream[SessionMessage | Exception], MemoryObjectSendStream[SessionMessage]], None
+]:
     """Client transport for stdio: this will connect to a server by spawning a
     process and communicating with it over stdin/stdout.
     """
@@ -134,7 +139,7 @@ async def stdio_client(server: StdioServerParameters, errlog: TextIO = sys.stder
         await write_stream_reader.aclose()
         raise
 
-    async def stdout_reader():
+    async def stdout_reader() -> None:
         assert process.stdout, "Opened process is missing stdout"
 
         try:
@@ -161,7 +166,7 @@ async def stdout_reader():
         except anyio.ClosedResourceError:  # pragma: lax no cover
             await anyio.lowlevel.checkpoint()
 
-    async def stdin_writer():
+    async def stdin_writer() -> None:
         assert process.stdin, "Opened process is missing stdin"
 
         try:
@@ -232,7 +237,7 @@ async def _create_platform_compatible_process(
     env: dict[str, str] | None = None,
     errlog: TextIO = sys.stderr,
     cwd: Path | str | None = None,
-):
+) -> Process | FallbackProcess:
     """Creates a subprocess in a platform-compatible way.
 
     Unix: Creates process in a new session/process group for killpg support
diff --git a/src/mcp/client/streamable_http.py b/src/mcp/client/streamable_http.py
index 3afb94b03..4a31835cd 100644
--- a/src/mcp/client/streamable_http.py
+++ b/src/mcp/client/streamable_http.py
@@ -466,7 +466,7 @@ async def post_writer(
                         read_stream_writer=read_stream_writer,
                     )
 
-                    async def handle_request_async():
+                    async def handle_request_async() -> None:
                         if is_resumption:
                             await self._handle_resumption_request(ctx)
                         else:
diff --git a/src/mcp/client/websocket.py b/src/mcp/client/websocket.py
index de473f36d..e5a7b58d8 100644
--- a/src/mcp/client/websocket.py
+++ b/src/mcp/client/websocket.py
@@ -43,7 +43,7 @@ async def websocket_client(
         read_stream_writer, read_stream = anyio.create_memory_object_stream(0)
         write_stream, write_stream_reader = anyio.create_memory_object_stream(0)
 
-        async def ws_reader():
+        async def ws_reader() -> None:
             """Reads text messages from the WebSocket, parses them as JSON-RPC messages,
             and sends them into read_stream_writer.
             """
@@ -57,7 +57,7 @@ async def ws_reader():
                         # If JSON parse or model validation fails, send the exception
                         await read_stream_writer.send(exc)
 
-        async def ws_writer():
+        async def ws_writer() -> None:
             """Reads JSON-RPC messages from write_stream_reader and
             sends them to the server.
             """
diff --git a/src/mcp/os/win32/utilities.py b/src/mcp/os/win32/utilities.py
index 6f68405f7..22dc600c0 100644
--- a/src/mcp/os/win32/utilities.py
+++ b/src/mcp/os/win32/utilities.py
@@ -80,7 +80,7 @@ def __init__(self, popen_obj: subprocess.Popen[bytes]):
         self.stdin = FileWriteStream(cast(BinaryIO, self.stdin_raw)) if self.stdin_raw else None
         self.stdout = FileReadStream(cast(BinaryIO, self.stdout_raw)) if self.stdout_raw else None
 
-    async def __aenter__(self):
+    async def __aenter__(self) -> "FallbackProcess":
         """Support async context manager entry."""
         return self
 
@@ -106,11 +106,11 @@ async def __aexit__(
         if self.stderr:
             self.stderr.close()
 
-    async def wait(self):
+    async def wait(self) -> int:
         """Async wait for process completion."""
         return await to_thread.run_sync(self.popen.wait)
 
-    def terminate(self):
+    def terminate(self) -> None:
         """Terminate the subprocess immediately."""
         return self.popen.terminate()
 
@@ -313,7 +313,7 @@ async def terminate_windows_process_tree(process: Process | FallbackProcess, tim
     "terminate_windows_process is deprecated and will be removed in a future version. "
     "Process termination is now handled internally by the stdio_client context manager."
 )
-async def terminate_windows_process(process: Process | FallbackProcess):
+async def terminate_windows_process(process: Process | FallbackProcess) -> None:
     """Terminate a Windows process.
 
     Note: On Windows, terminating a process with process.terminate() doesn't
diff --git a/src/mcp/server/__main__.py b/src/mcp/server/__main__.py
index dbc50b8a7..5d66cfb63 100644
--- a/src/mcp/server/__main__.py
+++ b/src/mcp/server/__main__.py
@@ -17,7 +17,7 @@
 logger = logging.getLogger("server")
 
 
-async def receive_loop(session: ServerSession):
+async def receive_loop(session: ServerSession) -> None:
     logger.info("Starting receive loop")
     async for message in session.incoming_messages:
         if isinstance(message, Exception):
@@ -27,7 +27,7 @@ async def receive_loop(session: ServerSession):
         logger.info("Received message from client: %s", message)
 
 
-async def main():
+async def main() -> None:
     version = importlib.metadata.version("mcp")
     async with stdio_server() as (read_stream, write_stream):
         async with (
diff --git a/src/mcp/server/auth/handlers/authorize.py b/src/mcp/server/auth/handlers/authorize.py
index dec6713b1..e5763a028 100644
--- a/src/mcp/server/auth/handlers/authorize.py
+++ b/src/mcp/server/auth/handlers/authorize.py
@@ -80,7 +80,7 @@ async def error_response(
             error: AuthorizationErrorCode,
             error_description: str | None,
             attempt_load_client: bool = True,
-        ):
+        ) -> Response:
             # Error responses take two different formats:
             # 1. The request has a valid client ID & redirect_uri: we issue a redirect
             #    back to the redirect_uri with the error response fields as query
diff --git a/src/mcp/server/auth/handlers/token.py b/src/mcp/server/auth/handlers/token.py
index 534a478a9..486249f21 100644
--- a/src/mcp/server/auth/handlers/token.py
+++ b/src/mcp/server/auth/handlers/token.py
@@ -6,6 +6,7 @@
 
 from pydantic import AnyHttpUrl, AnyUrl, BaseModel, Field, TypeAdapter, ValidationError
 from starlette.requests import Request
+from starlette.responses import Response
 
 from mcp.server.auth.errors import stringify_pydantic_error
 from mcp.server.auth.json_response import PydanticJSONResponse
@@ -63,7 +64,7 @@ class TokenHandler:
     provider: OAuthAuthorizationServerProvider[Any, Any, Any]
     client_authenticator: ClientAuthenticator
 
-    def response(self, obj: TokenSuccessResponse | TokenErrorResponse):
+    def response(self, obj: TokenSuccessResponse | TokenErrorResponse) -> PydanticJSONResponse:
         status_code = 200
         if isinstance(obj, TokenErrorResponse):
             status_code = 400
@@ -77,7 +78,7 @@ def response(self, obj: TokenSuccessResponse | TokenErrorResponse):
             },
         )
 
-    async def handle(self, request: Request):
+    async def handle(self, request: Request) -> Response:
         try:
             client_info = await self.client_authenticator.authenticate_request(request)
         except AuthenticationError as e:
diff --git a/src/mcp/server/auth/middleware/auth_context.py b/src/mcp/server/auth/middleware/auth_context.py
index 1d34a5546..682b3e47a 100644
--- a/src/mcp/server/auth/middleware/auth_context.py
+++ b/src/mcp/server/auth/middleware/auth_context.py
@@ -32,7 +32,7 @@ class AuthContextMiddleware:
     def __init__(self, app: ASGIApp):
         self.app = app
 
-    async def __call__(self, scope: Scope, receive: Receive, send: Send):
+    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
         user = scope.get("user")
         if isinstance(user, AuthenticatedUser):
             # Set the authenticated user in the contextvar
diff --git a/src/mcp/server/auth/middleware/bearer_auth.py b/src/mcp/server/auth/middleware/bearer_auth.py
index 6825c00b9..bc8b5263e 100644
--- a/src/mcp/server/auth/middleware/bearer_auth.py
+++ b/src/mcp/server/auth/middleware/bearer_auth.py
@@ -25,7 +25,7 @@ class BearerAuthBackend(AuthenticationBackend):
     def __init__(self, token_verifier: TokenVerifier):
         self.token_verifier = token_verifier
 
-    async def authenticate(self, conn: HTTPConnection):
+    async def authenticate(self, conn: HTTPConnection) -> tuple[AuthCredentials, AuthenticatedUser] | None:
         auth_header = next(
             (conn.headers.get(key) for key in conn.headers if key.lower() == "authorization"),
             None,
diff --git a/src/mcp/server/auth/routes.py b/src/mcp/server/auth/routes.py
index a72e81947..04905a1c0 100644
--- a/src/mcp/server/auth/routes.py
+++ b/src/mcp/server/auth/routes.py
@@ -21,7 +21,7 @@
 from mcp.shared.auth import OAuthMetadata, ProtectedResourceMetadata
 
 
-def validate_issuer_url(url: AnyHttpUrl):
+def validate_issuer_url(url: AnyHttpUrl) -> None:
     """Validate that the issuer URL meets OAuth 2.0 requirements.
 
     Args:
diff --git a/src/mcp/server/lowlevel/server.py b/src/mcp/server/lowlevel/server.py
index c28842272..408f2536b 100644
--- a/src/mcp/server/lowlevel/server.py
+++ b/src/mcp/server/lowlevel/server.py
@@ -368,7 +368,7 @@ async def run(
         # the initialization lifecycle, but can do so with any available node
         # rather than requiring initialization for each connection.
         stateless: bool = False,
-    ):
+    ) -> None:
         async with AsyncExitStack() as stack:
             lifespan_context = await stack.enter_async_context(self.lifespan(self))
             session = await stack.enter_async_context(
@@ -411,7 +411,7 @@ async def _handle_message(
         session: ServerSession,
         lifespan_context: LifespanResultT,
         raise_exceptions: bool = False,
-    ):
+    ) -> None:
         with warnings.catch_warnings(record=True) as w:
             match message:
                 case RequestResponder() as responder:
@@ -436,7 +436,7 @@ async def _handle_request(
         session: ServerSession,
         lifespan_context: LifespanResultT,
         raise_exceptions: bool,
-    ):
+    ) -> None:
         logger.info("Processing request of type %s", type(req).__name__)
 
         if handler := self._request_handlers.get(req.method):
diff --git a/src/mcp/server/mcpserver/context.py b/src/mcp/server/mcpserver/context.py
index 1538adc7c..3ad8391ed 100644
--- a/src/mcp/server/mcpserver/context.py
+++ b/src/mcp/server/mcpserver/context.py
@@ -14,6 +14,7 @@
     elicit_with_validation,
 )
 from mcp.server.lowlevel.helper_types import ReadResourceContents
+from mcp.server.session import ServerSession
 
 if TYPE_CHECKING:
     from mcp.server.mcpserver.server import MCPServer
@@ -224,7 +225,7 @@ def request_id(self) -> str:
         return str(self.request_context.request_id)
 
     @property
-    def session(self):
+    def session(self) -> ServerSession:
         """Access to the underlying session for advanced usage."""
         return self.request_context.session
 
diff --git a/src/mcp/server/mcpserver/server.py b/src/mcp/server/mcpserver/server.py
index 2a7a58117..afa3653ee 100644
--- a/src/mcp/server/mcpserver/server.py
+++ b/src/mcp/server/mcpserver/server.py
@@ -570,7 +570,7 @@ def decorator(fn: _CallableT) -> _CallableT:
 
         return decorator
 
-    def completion(self):
+    def completion(self) -> Callable[[_CallableT], _CallableT]:
         """Decorator to register a completion handler.
 
         The completion handler receives:
@@ -799,7 +799,7 @@ def custom_route(
         methods: list[str],
         name: str | None = None,
         include_in_schema: bool = True,
-    ):
+    ) -> Callable[[Callable[[Request], Awaitable[Response]]], Callable[[Request], Awaitable[Response]]]:
         """Decorator to register a custom HTTP route on the MCP server.
 
         Allows adding arbitrary HTTP endpoints outside the standard MCP protocol,
@@ -926,7 +926,7 @@ def sse_app(
 
         sse = SseServerTransport(message_path, security_settings=transport_security)
 
-        async def handle_sse(scope: Scope, receive: Receive, send: Send):  # pragma: no cover
+        async def handle_sse(scope: Scope, receive: Receive, send: Send) -> Response:  # pragma: no cover
             # Add client ID from auth context into request context if available
 
             async with sse.connect_sse(scope, receive, send) as streams:
diff --git a/src/mcp/server/session.py b/src/mcp/server/session.py
index ce467e6c9..79ad72466 100644
--- a/src/mcp/server/session.py
+++ b/src/mcp/server/session.py
@@ -161,7 +161,7 @@ async def _receive_loop(self) -> None:
         async with self._incoming_message_stream_writer:
             await super()._receive_loop()
 
-    async def _received_request(self, responder: RequestResponder[types.ClientRequest, types.ServerResult]):
+    async def _received_request(self, responder: RequestResponder[types.ClientRequest, types.ServerResult]) -> None:
         match responder.request:
             case types.InitializeRequest(params=params):
                 requested_version = params.protocol_version
diff --git a/src/mcp/server/sse.py b/src/mcp/server/sse.py
index 9dcee67f7..ab53a802e 100644
--- a/src/mcp/server/sse.py
+++ b/src/mcp/server/sse.py
@@ -37,6 +37,7 @@ async def handle_sse(request):
 """
 
 import logging
+from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
 from typing import Any
 from urllib.parse import quote
@@ -116,7 +117,11 @@ def __init__(self, endpoint: str, security_settings: TransportSecuritySettings |
         logger.debug(f"SseServerTransport initialized with endpoint: {endpoint}")
 
     @asynccontextmanager
-    async def connect_sse(self, scope: Scope, receive: Receive, send: Send):  # pragma: no cover
+    async def connect_sse(
+        self, scope: Scope, receive: Receive, send: Send
+    ) -> AsyncGenerator[
+        tuple[MemoryObjectReceiveStream[SessionMessage | Exception], MemoryObjectSendStream[SessionMessage]], None
+    ]:  # pragma: no cover
         if scope["type"] != "http":
             logger.error("connect_sse received non-HTTP request")
             raise ValueError("connect_sse can only handle HTTP requests")
@@ -159,7 +164,7 @@ async def connect_sse(self, scope: Scope, receive: Receive, send: Send):  # prag
 
         sse_stream_writer, sse_stream_reader = anyio.create_memory_object_stream[dict[str, Any]](0)
 
-        async def sse_writer():
+        async def sse_writer() -> None:
             logger.debug("Starting SSE writer")
             async with sse_stream_writer, write_stream_reader:
                 await sse_stream_writer.send({"event": "endpoint", "data": client_post_uri_data})
@@ -176,7 +181,7 @@ async def sse_writer():
 
         async with anyio.create_task_group() as tg:
 
-            async def response_wrapper(scope: Scope, receive: Receive, send: Send):
+            async def response_wrapper(scope: Scope, receive: Receive, send: Send) -> None:
                 """The EventSourceResponse returning signals a client close / disconnect.
                 In this case we close our side of the streams to signal the client that
                 the connection has been closed.
diff --git a/src/mcp/server/stdio.py b/src/mcp/server/stdio.py
index 5ea6c4e77..f393fb9aa 100644
--- a/src/mcp/server/stdio.py
+++ b/src/mcp/server/stdio.py
@@ -18,6 +18,7 @@ async def run_server():
 """
 
 import sys
+from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
 from io import TextIOWrapper
 
@@ -30,7 +31,11 @@ async def run_server():
 
 
 @asynccontextmanager
-async def stdio_server(stdin: anyio.AsyncFile[str] | None = None, stdout: anyio.AsyncFile[str] | None = None):
+async def stdio_server(
+    stdin: anyio.AsyncFile[str] | None = None, stdout: anyio.AsyncFile[str] | None = None
+) -> AsyncGenerator[
+    tuple[MemoryObjectReceiveStream[SessionMessage | Exception], MemoryObjectSendStream[SessionMessage]], None
+]:
     """Server transport for stdio: this communicates with an MCP client by reading
     from the current process' stdin and writing to stdout.
     """
@@ -52,7 +57,7 @@ async def stdio_server(stdin: anyio.AsyncFile[str] | None = None, stdout: anyio.
     read_stream_writer, read_stream = anyio.create_memory_object_stream(0)
     write_stream, write_stream_reader = anyio.create_memory_object_stream(0)
 
-    async def stdin_reader():
+    async def stdin_reader() -> None:
         try:
             async with read_stream_writer:
                 async for line in stdin:
@@ -67,7 +72,7 @@ async def stdin_reader():
         except anyio.ClosedResourceError:  # pragma: no cover
             await anyio.lowlevel.checkpoint()
 
-    async def stdout_writer():
+    async def stdout_writer() -> None:
         try:
             async with write_stream_reader:
                 async for session_message in write_stream_reader:
diff --git a/src/mcp/server/streamable_http.py b/src/mcp/server/streamable_http.py
index aa99e7c88..db1274fa6 100644
--- a/src/mcp/server/streamable_http.py
+++ b/src/mcp/server/streamable_http.py
@@ -577,7 +577,7 @@ async def _handle_post_request(self, scope: Scope, request: Request, receive: Re
                 # Store writer reference so close_sse_stream() can close it
                 self._sse_stream_writers[request_id] = sse_stream_writer
 
-                async def sse_writer():  # pragma: lax no cover
+                async def sse_writer() -> None:  # pragma: lax no cover
                     # Get the request ID from the incoming request message
                     try:
                         async with sse_stream_writer, request_stream_reader:
@@ -696,7 +696,7 @@ async def _handle_get_request(self, request: Request, send: Send) -> None:
         # Create SSE stream
         sse_stream_writer, sse_stream_reader = anyio.create_memory_object_stream[dict[str, str]](0)
 
-        async def standalone_sse_writer():
+        async def standalone_sse_writer() -> None:
             try:
                 # Create a standalone message stream for server-initiated messages
 
@@ -890,7 +890,7 @@ async def _replay_events(self, last_event_id: str, request: Request, send: Send)
             # Create SSE stream for replay
             sse_stream_writer, sse_stream_reader = anyio.create_memory_object_stream[dict[str, str]](0)
 
-            async def replay_sender():
+            async def replay_sender() -> None:
                 try:
                     async with sse_stream_writer:
                         # Define an async callback for sending events
@@ -979,7 +979,7 @@ async def connect(
         # Start a task group for message routing
         async with anyio.create_task_group() as tg:
             # Create a message router that distributes messages to request streams
-            async def message_router():
+            async def message_router() -> None:
                 try:
                     async for session_message in write_stream_reader:  # pragma: no branch
                         # Determine which request stream(s) should receive this message
diff --git a/src/mcp/server/streamable_http_manager.py b/src/mcp/server/streamable_http_manager.py
index c25314eab..8e60863ed 100644
--- a/src/mcp/server/streamable_http_manager.py
+++ b/src/mcp/server/streamable_http_manager.py
@@ -162,7 +162,7 @@ async def _handle_stateless_request(self, scope: Scope, receive: Receive, send:
         )
 
         # Start server in a new task
-        async def run_stateless_server(*, task_status: TaskStatus[None] = anyio.TASK_STATUS_IGNORED):
+        async def run_stateless_server(*, task_status: TaskStatus[None] = anyio.TASK_STATUS_IGNORED) -> None:
             async with http_transport.connect() as streams:
                 read_stream, write_stream = streams
                 task_status.started()
diff --git a/src/mcp/server/websocket.py b/src/mcp/server/websocket.py
index 32b50560c..79623d7ba 100644
--- a/src/mcp/server/websocket.py
+++ b/src/mcp/server/websocket.py
@@ -1,3 +1,4 @@
+from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
 
 import anyio
@@ -11,7 +12,11 @@
 
 
 @asynccontextmanager
-async def websocket_server(scope: Scope, receive: Receive, send: Send):
+async def websocket_server(
+    scope: Scope, receive: Receive, send: Send
+) -> AsyncGenerator[
+    tuple[MemoryObjectReceiveStream[SessionMessage | Exception], MemoryObjectSendStream[SessionMessage]], None
+]:
     """WebSocket server transport for MCP. This is an ASGI application, suitable for use
     with a framework like Starlette and a server like Hypercorn.
     """
@@ -28,7 +33,7 @@ async def websocket_server(scope: Scope, receive: Receive, send: Send):
     read_stream_writer, read_stream = anyio.create_memory_object_stream(0)
     write_stream, write_stream_reader = anyio.create_memory_object_stream(0)
 
-    async def ws_reader():
+    async def ws_reader() -> None:
         try:
             async with read_stream_writer:
                 async for msg in websocket.iter_text():
@@ -43,7 +48,7 @@ async def ws_reader():
         except anyio.ClosedResourceError:  # pragma: no cover
             await websocket.close()
 
-    async def ws_writer():
+    async def ws_writer() -> None:
         try:
             async with write_stream_reader:
                 async for session_message in write_stream_reader:
diff --git a/tests/test_examples.py b/tests/test_examples.py
index 3af82f04c..3b9cdb23a 100644
--- a/tests/test_examples.py
+++ b/tests/test_examples.py
@@ -96,7 +96,7 @@ async def test_desktop(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
 # TODO(v2): Change back to README.md when v2 is released
 @pytest.mark.parametrize("example", find_examples("README.v2.md"), ids=str)
 def test_docs_examples(example: CodeExample, eval_example: EvalExample):
-    ruff_ignore: list[str] = ["F841", "I001", "F821"]  # F821: undefined names (snippets lack imports)
+    ruff_ignore: list[str] = ["F841", "I001", "F821", "ANN"]  # F821: undefined names (snippets lack imports)
 
     # Use project's actual line length of 120
     eval_example.set_config(ruff_ignore=ruff_ignore, target_version="py310", line_length=120)