diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2aa16144..9223152b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ All notable changes to `mcp/sdk` will be documented in this file.
 * Add `LenientOidcDiscoveryMetadataPolicy` for identity providers that omit `code_challenge_methods_supported` (e.g. FusionAuth, Microsoft Entra ID)
 * Add OAuth 2.0 Dynamic Client Registration middleware (RFC 7591)
 * Add optional `title` field to `Prompt` and `McpPrompt` for MCP spec compliance
+* Fix PHPDoc type of `GetPromptRequest::$arguments` from `array<string, mixed>` to `array<string, string>` per MCP spec
 * [BC Break] `Builder::addPrompt()` signature changed — `$title` parameter added between `$name` and `$description`. Callers using positional arguments for `$description` must switch to named arguments.
 
 0.4.0
diff --git a/src/Schema/Request/GetPromptRequest.php b/src/Schema/Request/GetPromptRequest.php
index bc6903f3..ea0aa3c9 100644
--- a/src/Schema/Request/GetPromptRequest.php
+++ b/src/Schema/Request/GetPromptRequest.php
@@ -23,7 +23,7 @@ final class GetPromptRequest extends Request
 {
     /**
      * @param string                    $name      the name of the prompt to get
-     * @param array<string, mixed>|null $arguments the arguments to pass to the prompt
+     * @param array<string, string>|null $arguments the arguments to pass to the prompt
      */
     public function __construct(
         public readonly string $name,
@@ -56,7 +56,7 @@ protected static function fromParams(?array $params): static
     }
 
     /**
-     * @return array{name: string, arguments?: array<string, mixed>}
+     * @return array{name: string, arguments?: array<string, string>}
      */
     protected function getParams(): array
     {