mcptools 0.2.0

Server

• mcp_server() now supports HTTP transport in addition to stdio. Use type = "http" to start an HTTP server, with optional host and port arguments. For now, the implementation is authless.

• mcp_server() now formats tool results in the same way as ellmer (#78 by @gadenbuie).

• mcp_server() gains logical argument session_tools, allowing users to opt-out of presenting R session tools (that make it possible to communicate with mcp_session()s) to clients.

• Several tightenings-up of the implementation:

  • JSON-RPC responses now retain an explicit id = NULL value, ensuring parse-error replies conform to the MCP specification.
  • The implementation now supports the 2025-06-18 protocol version, updated from 2024-11-05.

• mcp_session() now invisibly returns the nanonext socket used for communicating with the server.

Client

• Notably, mcp_tools() did not gain an implementation of the HTTP transport. Instead, we now recommend the mcp-remote tool for serving local MCP servers via the HTTP transport in the documentation.

• mcp_tools() now errors more informatively when an MCP server process exits unexpectedly (#82).

• mcp_tools() now sends and receives a "notifications/initialized", resolving issues connecting to some MCP servers like fastMCP (#77 by @galachad).