mcp

A minimal MCP (Model Context Protocol) client (EXPERIMENTAL x/ tier, #6 S9). MCP is JSON-RPC 2.0 over a transport; this client composes the landed substrate — cx-stdlib/jsonrpc (message model), cx-stdlib/jsonschema (validates tool inputs), the real cx-stdlib/http client (Streamable-HTTP transport), and cx-stdlib/json — with no new transport and no V backing. Pure request builders (initialize/list-tools/call-tool) + response extractors (tools-of, result-text) + validate-args are split from the effectful transport (rpc-call, list-tools, call-tool). A remote tool composes as a cx-x/run Runnable via the call-site closure idiom. stdio transport + the initialize-handshake session state are later increments.

Experimental x/ tier — imported as cx-x/mcp. Bundled and gated in-tree like any other module, but EXEMPT from the frozen-surface stability promise (std-lib README, decision D3): a semver-breaking change is allowed here while the surface settles, and the frozen-surface canary never counts it. Pin behaviour you depend on with your own fixtures.