[dependabot]

Bumps @modelcontextprotocol/express from 2.0.0 to 2.0.2.

Release notes

Sourced from @​modelcontextprotocol/express's releases.

@​modelcontextprotocol/express@​2.0.2

Patch Changes

• #2929 40f8f4e Thanks @​claude! - requireBearerAuth and verifyBearerToken take a new optional expectedResource, which makes them accept only tokens issued for this resource (the token's audience). Set it to the value your authorization server puts into tokens meant for this server, usually the server's URL. When it is set, a token is accepted only if the verifier reports that value in AuthInfo.resource; the two are compared as strings, ignoring a fragment and one trailing slash. A token reported for another value, or for none, is answered 401 invalid_token with the usual WWW-Authenticate challenge. When it is not set, nothing changes. To use it, pass expectedResource and have verifyAccessToken fill AuthInfo.resource, for example from the aud claim. The option is declared on a new exported type, VerifyBearerTokenOptions, which extends BearerAuthOptions; BearerAuthOptions itself is unchanged. The Express requireBearerAuth passes the option through. With Express, @modelcontextprotocol/express has to be upgraded to this release as well: 2.0.1 does not pass the option on, so nothing is compared. Its options type does not have the option, so TypeScript reports an expectedResource written in a call to the 2.0.1 requireBearerAuth as an error.

• #2918 84804c2 Thanks @​claude! - A Server or McpServer now serves one connection at a time, and a Streamable HTTP server transport without sessions (sessionIdGenerator: undefined) serves one request. An app that uses one server object, or one stateless transport, for every HTTP request fails on the second request after this upgrade. Build the server and the transport per request instead.

  What keeps working without a change:

  • createMcpHandler(buildServer) and serveStdio(buildServer), where buildServer returns a new server on every call.
  • A handler that builds a new server and a new stateless transport for each request.
  • One server and one transport per session (a transport with a sessionIdGenerator).
  • Connecting a server again after close().
  • Client.

  What fails now, how it shows, and what to change:

  • One server object with a new stateless transport per request (const server = new McpServer(...) outside the handler, await server.connect(transport) inside it): the second HTTP request the process receives fails, and so does every later one. connect() rejects with an SdkError of code ALREADY_CONNECTED. If the handler closes the transport when the response ends, requests that arrive one after the other still work and a request that overlaps another one fails. Change: move new McpServer(...) and its registrations into the handler.
  • One stateless transport for every request (a transport built once with sessionIdGenerator: undefined): the second HTTP request fails. WebStandardStreamableHTTPServerTransport.handleRequest() rejects with Stateless transport cannot be reused across requests. Create a new transport per request., and NodeStreamableHTTPServerTransport.handleRequest() answers 500. Change: build the server and the transport inside the handler and connect them there.
  • createMcpHandler(() => server) with a server built once: a request that arrives after the previous response has been read to its end still works. A request that arrives while another one is being served is answered 500 with the JSON-RPC error -32603 (Internal server error); the reason is reported only through the onerror option. Change: pass a function that builds the server, as in createMcpHandler(buildServer).
  • One server object for every session: the initialize request of the second session fails with ALREADY_CONNECTED. Change: build a server per session.

  What the caller sees when connect() or handleRequest() rejects depends on the host. Express 5, Fastify and Hono answer 500. A plain node:http listener without its own error handling gets an unhandled rejection, which ends the process.

  The README examples of @modelcontextprotocol/express, @modelcontextprotocol/fastify, @modelcontextprotocol/hono and @modelcontextprotocol/node, and the handler examples in the JSDoc of WebStandardStreamableHTTPServerTransport and NodeStreamableHTTPServerTransport, now build a server and a transport per request.

• #2908 633dd3e Thanks @​claude! - The license field of the package manifests is now Apache-2.0; the LICENSE file shipped in each package carries the full terms, including the MIT text for earlier contributions. No code change.

• Updated dependencies [40f8f4e, 6d8dbc6, 5238fba, 2fc49ea, 4d94e7b, 84804c2, e55f9ac, 633dd3e, 2237555]:

  • @​modelcontextprotocol/server@​2.3.0

@​modelcontextprotocol/express@​2.0.1

Patch Changes

• #2698 7b781ed Thanks @​maxisbey! - Read Streamable HTTP request bodies with a size limit. Every SDK-owned body read — WebStandardStreamableHTTPServerTransport (and the Node transport built on it), createMcpHandler, toNodeHandler, and createMcpHonoApp's JSON pre-parse — now stops at 4 MiB by default (the limit the legacy SSE transport already uses; the Express adapter and stdio bound their reads too) and answers 413 Payload Too Large before anything is parsed. toWebRequest (when it reads the Node stream itself) now rejects once the body exceeds the limit with an error whose name is 'RequestBodyTooLargeError' and status is 413, and toNodeHandler answers that with 413; hand-wired callers of toWebRequest should handle the rejection or pass a pre-parsed body, and isLegacyRequest reports such a request as non-legacy so the modern handler answers it. JSON-RPC batch arrays are limited to 100 messages; a longer batch is answered 400 / -32600 and none of it is dispatched.

  The limit is configurable with a new maxRequestBodySize option (bytes, default DEFAULT_MAX_REQUEST_BODY_SIZE = 4 MiB, exported from @modelcontextprotocol/server) on WebStandardStreamableHTTPServerTransportOptions, CreateMcpHandlerOptions (forwarded to its stateless legacy leg; isLegacyRequest and legacyStatelessFallback take the same option), CreateMcpHonoAppOptions, and ToNodeHandlerOptions / ToWebRequestOptions (the adapter's bound applies before the handler's, so raise both). The bounded reader is exported as

... (truncated)

Commits

• a202a36 Version Packages (#2896)
• 2d731fa fix(client): refresh again when an SSE retry failed for a reason other than 4...
• b6e5c55 test(e2e): cover prompts/get without arguments for prompts with a schema (#2928)
• 40f8f4e feat(server): add expectedResource to the bearer-token check (#2929)
• 6d8dbc6 feat(server): add maxToolInputElements option to limit the number of elements...
• 2fc49ea fix(server): accept prompts/get requests that omit arguments (#2107)
• 63c0fca fix(client): update eventsource-parser for large SSE responses (#2846)
• 84804c2 fix(server): refuse a second connect and stateless transport reuse (#2918)
• e16d277 docs: close idle sessions and cap the session map in the sessions guide and e...
• 433eb41 fix(client): follow redirects only within the origin of the request (#2901)
• Additional commits viewable in compare view

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