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Filename Latest commit message Latest commit date
jh-block 01a6666429
 fix: treat resource metadata JSON parse failure as soft error (#810) 
In fetch_resource_metadata_from_url, a JSON parse failure on the
response body caused a fatal AuthError::MetadataError, preventing
discover_metadata() from falling through to direct
.well-known/oauth-authorization-server discovery (Strategy B).

MCP servers that return HTTP 200 with non-JSON content (e.g. HTML)
at their base URL caused the OAuth flow to abort entirely, even
when the server had a valid .well-known/oauth-authorization-server
endpoint.

Return Ok(None) on parse failure, consistent with how HTTP errors
are already handled in the same function.
2026-04-16 12:16:19 -04:00
..
src fix: treat resource metadata JSON parse failure as soft error (#810) 2026-04-16 12:16:19 -04:00
tests fix: include http_request_id in request-wise priming event IDs (#799) 2026-04-16 12:02:35 -04:00
build.rs chore: add pre-commit hook for conventional commit verification (#619) 2026-01-14 16:01:28 -05:00
Cargo.toml fix(http): drain SSE stream for connection reuse (#790) 2026-04-13 16:33:30 -04:00
CHANGELOG.md chore: release v1.4.0 (#779) 2026-04-10 10:40:38 -04:00
README.md feat: add local feature for !Send tool handler support (#740) 2026-03-11 17:22:56 -04:00

README.md

rmcp

Crates.io Documentation

The official Rust SDK for the Model Context Protocol. Build MCP servers that expose tools, resources, and prompts to AI assistants — or build clients that connect to them.

For getting started, usage guides, and full MCP feature documentation (resources, prompts, sampling, roots, logging, completions, subscriptions, etc.), see the main README.

Feature Flags

Feature Description Default
server Server functionality and the tool system ✅
client Client functionality
macros #[tool] / #[prompt] macros (re-exports rmcp-macros) ✅
schemars JSON Schema generation for tool definitions
auth OAuth 2.0 authentication support
elicitation Elicitation support

Transport features

Feature Description
transport-io Server-side stdio transport
transport-child-process Client-side stdio transport (spawns a child process)
transport-async-rw Generic async read/write transport
transport-streamable-http-client Streamable HTTP client (transport-agnostic)
transport-streamable-http-client-reqwest Streamable HTTP client with default reqwest backend
transport-streamable-http-server Streamable HTTP server transport

TLS backend options (for HTTP transports)

Feature Description
reqwest Uses rustls — pure Rust TLS (recommended default)
reqwest-native-tls Uses platform-native TLS (OpenSSL / Secure Transport / SChannel)
reqwest-tls-no-provider Uses rustls without a default crypto provider (bring your own)

Transports

The transport layer is pluggable. Two built-in pairs cover the most common cases:

Client Server
stdio TokioChildProcess stdio
Streamable HTTP StreamableHttpClientTransport StreamableHttpService

Any type that implements the Transport trait can be used. The IntoTransport helper trait provides automatic conversions from:

  1. (Sink, Stream) or a combined Sink + Stream
  2. (AsyncRead, AsyncWrite) or a combined AsyncRead + AsyncWrite
  3. A Worker implementation
  4. A Transport implementation directly

License

This project is licensed under the terms specified in the repository's LICENSE file.