[Phase 1.2] Python MCP Client Wrapper - Type Safety Improvements

[anchapin]

Summary

Implements type safety improvements to the Python MCP client wrapper to meet mypy --strict compliance.

Changes

• Add explicit type annotation for JSON-RPC response parsing to satisfy mypy --strict
• Add runtime type check for tool call results to ensure proper type safety
• Fix __exit__ return type from bool to None (PEP 343 compliance)

Testing

All 62 existing tests pass with 94% coverage (exceeds 75% target).

cd agent && .venv/bin/python -m pytest tests/test_mcp_client.py -v
# ============================== 62 passed in 1.38s ==============================

Code quality checks pass:

• ✅ mypy --strict: Success
• ✅ black: Compliant
• ✅ pylint: 9.23/10

Related Issue

Closes #517

Acceptance Criteria

✅ Create agent/mcp_client.py - COMPLETE
✅ Implement list_tools() method - COMPLETE
✅ Implement call_tool() method - COMPLETE
✅ Implement connection lifecycle (spawn, initialize, shutdown) - COMPLETE
✅ Add context manager support - COMPLETE
✅ Write tests using Hypothesis - COMPLETE
✅ Target 75% test coverage - EXCEEDED (94%)

Implementation Details

The Python MCP client wrapper provides a robust, secure interface to the MCP protocol:

• Security: Command validation with allowlist and metacharacter detection
• Reliability: 94% test coverage with comprehensive error handling
• Usability: Context manager support for automatic cleanup
• Type Safety: Full mypy --strict compliance

Example usage:

with McpClient("filesystem", ["npx", "-y", "@server/fs"]) as client:
    tools = client.list_tools()
    result = client.call_tool("read_file", {"path": "test.txt"})

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Co-Authored-By: Claude Sonnet 4.6 noreply@anthropic.com

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