Milestone M8 implementation adds MCP integration for connecting to external
tool servers and resources.
New crate: crates/integration/mcp-client
- JSON-RPC 2.0 protocol implementation
- Stdio transport for spawning MCP server processes
- Capability negotiation (initialize handshake)
- Tool operations:
* tools/list: List available tools from server
* tools/call: Invoke tools with arguments
- Resource operations:
* resources/list: List available resources
* resources/read: Read resource contents
- Async design using tokio for non-blocking I/O
MCP Client Features:
- McpClient: Main client with subprocess management
- ServerCapabilities: Capability discovery
- McpTool: Tool definitions with JSON schema
- McpResource: Resource definitions with URI/mime-type
- Automatic request ID management
- Error handling with proper JSON-RPC error codes
Permission Integration:
- Added Tool::Mcp to permission system
- Pattern matching support for mcp__server__tool format
* "filesystem__*" matches all filesystem server tools
* "filesystem__read_file" matches specific tool
- MCP requires Ask permission in Plan/AcceptEdits modes
- MCP allowed in Code mode (like Bash)
Tests added (3 new tests with mock Python servers):
1. mcp_server_capability_negotiation - Verifies initialize handshake
2. mcp_tool_invocation - Tests tool listing and calling
3. mcp_resource_reads - Tests resource listing and reading
Permission tests added (2 new tests):
1. mcp_server_pattern_matching - Verifies server-level wildcards
2. mcp_exact_tool_matching - Verifies tool-level exact matching
All 75 tests passing (up from 68).
Note: CLI integration deferred - MCP infrastructure is in place and fully
tested. Future work will add MCP server configuration and CLI commands to
invoke MCP tools.
Protocol: Implements MCP 2024-11-05 specification over stdio transport.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
