MCP

The read API mounts a stateless, streamable HTTP Model Context Protocol endpoint at:

http://localhost:8081/v1/mcp

Configure that URL as a streamable HTTP server in an MCP client. The transport supports POST for JSON-RPC invocation, GET for the stream, and DELETE for session termination semantics.

Cassette tools

The MCP server aggregates tools advertised by installed cassettes. A cassette marks an OpenAPI operation with x-tapes-mcp; Tapes validates its JSON-body contract and publishes it under a cassette-qualified name such as summary.summarize_session. tools/list reads the current cassette registry, so successfully refreshed cassettes appear without restarting Tapes and removed cassettes disappear.

Tool arguments are sent as the cassette operation’s JSON request body. A successful JSON object is returned as both MCP structured content and JSON text; non-2xx responses and unavailable cassettes are tool errors. Calls use the same admitted cassette origin and caller identity headers as the cassette HTTP proxy. See Cassettes for the extension and its initial POST-only constraints.

The transport is stateless, so it cannot push reliable out-of-band tool-list change notifications. A client connected while the cassette fleet changes may need to reconnect or issue tools/list again.

Legacy core search tool

While search is being extracted to its own cassette, configuring span search and the embedder still registers the core tool below:

The tool embeds the query and uses the same span search implementation as GET /v1/search/spans. Its structured results contain session_id, trace_id, span_id, score, user_prompt, snippet, model, and started_at for each matched main-conversation LLM span.

Example tool arguments:

{
  "query": "how was logging configured?",
  "top_k": 3
}

Enable it locally

tapes local up
tapes serve

The bundled local setup configures PostgreSQL/pgvector and Ollama embeddings, and tapes serve embeds spans by default. Capture or seed data before searching:

tapesctl seed --tapes-url http://localhost:8081

If search dependencies are not configured, the legacy core search tool is omitted; cassette tools remain available. If storage is configured but the span embedding projection is not initialized, core search reports an error until the embed worker populates it.

Scope

Header-less core MCP search uses the same nil-org tenant bucket as header-less HTTP search. Cassette tools can expose whatever behavior their admitted POST operation implements; MCP annotations are descriptive hints and do not replace gateway or cassette authorization.