fix(filesystem): describe tool parameters

[go165]

Description

Adds parameter-level descriptions to the filesystem server tools so tools/list exposes enough schema detail for agents to choose correct argument values.

The descriptions cover path shape and sandbox constraints, write/edit mutation scope, move source/destination behavior, and search/exclude glob semantics. This addresses #4095 for the filesystem server.

Server Details

• Server: filesystem
• Changes to: tool input schemas

Motivation and Context

Required filesystem tool parameters were exposed as typed schema properties without descriptions, so clients and agents had to infer whether values should be files, directories, glob patterns, or write content. The new descriptions make those expectations explicit in the MCP tool schema.

How Has This Been Tested?

• npm run build -w src/filesystem
• npm test -w src/filesystem

I added an integration test that starts the built filesystem server and checks tools/list to ensure every required tool parameter has a non-empty description.

Breaking Changes

None.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

No README update is needed because this only improves MCP tool schema metadata. I did not test with an LLM client; the regression test verifies the MCP tools/list schema surfaced to clients.