| Filename | Latest commit message | Latest commit date |
|---|---|---|
46db531df9* fix(sse): saturate exponential reconnect backoff ExponentialBackoff::retry computed the reconnect multiplier with 2u32.pow(current_times). With max_times unset, current_times can reach the bit width, panicking in debug builds and wrapping to a zero delay in release builds for long-lived SSE clients. Use saturating_pow and Duration::saturating_mul so the delay stays monotonic and panic-free. * fix(sse): cap exponential reconnect backoff at a bounded max delay Saturating the multiplier alone can still yield decades-long sleeps once current_times reaches the bit width, pinning the stream in tokio::time::sleep without reconnecting or terminating. Add an optional max_delay (default 30s) that clamps the computed delay, keeping the backoff monotonic and panic-free while guaranteeing the client retries. * fix(sse): default max_delay to None to preserve unbounded backoff Per maintainer feedback, leave ExponentialBackoff::default() unbounded so the fix stays a pure overflow bug-fix. The saturating multiplier removes the debug panic / release wrap from #1198, while max_delay stays opt-in for callers that want a bounded reconnect delay. |
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| .. | ||
| src | ||
| tests | ||
| build.rs | ||
| Cargo.toml | ||
| CHANGELOG.md | ||
| README.md | ||
rmcp
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 | |
auth-enterprise-managed |
EMA/XAA refresh-token and ID-JAG exchanges for registered public and confidential clients (includes auth) |
|
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) |
For enterprise-managed authorization, enable auth-enterprise-managed and a TLS
backend such as reqwest. See the EMA/XAA guide
for client authentication and an MCP connection example.
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:
(Sink, Stream)or a combinedSink + Stream(AsyncRead, AsyncWrite)or a combinedAsyncRead + AsyncWrite- A
Workerimplementation - A
Transportimplementation directly
License
This project is licensed under the terms specified in the repository's LICENSE file.