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brust

Every brust app is also an MCP server. The framework already knows what an agent needs — your actions are typed endpoints and your route loaders return structured data — so it exposes both over the Model Context Protocol (revision 2025-06-18) at:

POST /_brust/mcp        (JSON-RPC 2.0)

There is nothing to enable: brust.run() builds the manifest at boot and wires the server into every worker. The transport is plain HTTP POST — no SSE notifications or streaming (deferred) — which any MCP client that speaks Streamable HTTP can use, as can curl:

curl -s -X POST http://localhost:1337/_brust/mcp \
  -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

Tools — from defineActions

Each endpoint registered on the defineActions chain in your actions.ts becomes one tool, named <method>_<path-slug>: POST /notes → post_notes, GET /notes/{id} → get_notes_by_id, a root path → get_root. Two endpoints slugging to the same name fail the build; an endpoint with a non-literal path string is skipped with a warning.

Schemas are extracted from your TypeScript — no hand-written JSON Schema:

Schema part Source
inputSchema.params {x} segments in the path — each a required string.
inputSchema.body The endpoint's body validator, via the handler ctx type.
inputSchema.query The endpoint's query validator, likewise.
outputSchema The handler's return type (Promise unwrapped).
description The endpoint's description option.

tools/call arguments nest by routing role — { params?, query?, body? } — and dispatch through the same path as a real HTTP request: body/query validation (422 on failure), the endpoint middleware chain, and the typed error contract all apply identically. The same auth that protects users protects agents. The tool result carries the response body as text, with isError: true for any status ≥ 400.

Resources — from route loaders

Every route with a loader is listed as a resource at brust://<path-template> (e.g. brust:///pokemon/{name}). resources/read matches the URI against the route table — {param} segments capture — runs the loader, and returns its result as JSON. Output schemas for resources are not extracted yet.

The manifest

A boot-time extractor walks actions.ts and routes.tsx with the TypeScript compiler API and caches the result as .brust/mcp-manifest.json. brust build ships it as dist/mcp-manifest.json, so a deployed dist serves agents without doing any type analysis at boot. An app with no actions.ts exposes zero tools — loaders still become resources.

Protocol surface

Method Behavior
initialize Protocol 2025-06-18; capabilities: tools, resources, prompts, logging.
tools/list, tools/call As above.
resources/list, resources/read As above.
prompts/list Always empty (no prompts surface).
logging/setLevel Accepted; no notifications are emitted.

That is the whole surface today: tools and resources derived from code you already wrote, over POST. There is no separate agent SDK, CLI command, or configuration file.