* docs(server): document Err vs Ok(CallToolResult::error) visibility contract
The MCP spec separates two failure modes that surface very differently in
clients:
- Err(ErrorData) is a JSON-RPC protocol error. Most MCP clients render
it opaquely ("Tool result missing due to internal error") - the
caller does not see the message text.
- Ok(CallToolResult::error(content)) is a tool-level error. Clients
render the content; the caller reads the message.
The right shape for "the tool didn't work" is the latter, but Err is
what most handlers reach for because it looks like the natural Rust
return value. This commit adds rustdoc on both ServerHandler::call_tool
and CallToolResult::error pointing handlers at the correct shape, with
a worked example showing protocol errors (-32602 invalid_params) vs
tool errors (empty result, downstream failure).
This is the docs half of the visibility-contract ask. A follow-up may
introduce a typed ToolOutcome sum type to enforce the distinction at
compile time; this PR is the lower-risk version that unblocks the
class immediately.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
* docs: update crates/rmcp/src/handler/server.rs
* docs: update crates/rmcp/src/model.rs
---------
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: Dale Seo <5466341+DaleSeo@users.noreply.github.com>
* feat: implement SEP-2164 resource not found errors
* test: update protocol version utility expectations
* feat: gate not-found code at server boundary
---------
Co-authored-by: Michael Neale <michael.neale@gmail.com>
* feat(auth): specify OIDC application_type during client registration
SEP-837 [1] requires an MCP client to specify an application_type during
OIDC Dynamic Client Registration. When it is omitted, OIDC servers
default the client to "web", which conflicts with the loopback redirect
URIs that CLI and desktop clients use, so the registration can be
rejected.
I make register_client always send an application_type. It defaults to
"native" to match the loopback redirect this SDK uses, and I added
OAuthClientConfig::with_application_type so web clients can opt in. Tests
cover the serialized request body and the config default. Implements [2].
[1]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/main/docs/specification/draft/basic/authorization.mdx#L395
[2]: https://github.com/modelcontextprotocol/rust-sdk/issues/880
Signed-off-by: Stefano Amorelli <stefano@amorelli.tech>
* chore(auth): declare application_type in client metadata document
I set application_type to "native" in the hosted client metadata
document so the URL-based client id flow and dynamic registration agree
on the client type that SEP-837 [1] expects.
[1]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/main/docs/specification/draft/basic/authorization.mdx#L395
Signed-off-by: Stefano Amorelli <stefano@amorelli.tech>
---------
Signed-off-by: Stefano Amorelli <stefano@amorelli.tech>
SEP-2577 deprecates the Roots, Sampling, and Logging features. The
deprecation is advisory: the features stay fully functional and there is
no wire-level change. Mark the corresponding Rust APIs as deprecated so
downstream users get compiler warnings and migration guidance.
- Forward attributes through the service `method!` macros and deprecate
`Peer::create_message`, `Peer::list_roots`, `Peer::set_level`, and
`Peer::notify_logging_message`.
- Forward per-field attributes through the capability `builder!` macro and
deprecate the generated `enable_roots`, `enable_sampling`, and
`enable_logging` builders, plus the hand-written
`enable_roots_list_changed`, `enable_sampling_tools`, and
`enable_sampling_context`.
- Document the deprecation on the capability types and fields, and in the
README feature sections.
- Allow `deprecated` at the crate's own call sites so the build stays
warning-clean, and refresh the message schema snapshots.
The Resource variant of PromptMessageContent was missing #[serde(flatten)],
causing the embedded resource content block to serialize as a double-nested
shape `{ "type": "resource", "resource": { "resource": {...} } }` instead of
the spec-compliant flat shape `{ "type": "resource", "resource": {uri, mimeType, text} }`.
This caused Zod-based MCP clients (e.g. Claude Code) to reject prompts/get
responses containing embedded resource messages with InvalidUnion errors.
The Image and ResourceLink variants already use #[serde(flatten)] correctly;
only Resource was missing it.
Fix: add #[serde(flatten)] so EmbeddedResource (=Annotated<RawEmbeddedResource>)
fields _meta / annotations / resource are flattened to the content-block level,
matching the MCP spec for prompts embedded resources.
Regression test: test_prompt_message_resource_serialization_is_flat verifies
content.resource.uri is reachable and content.resource.resource is absent.
Schema snapshots regenerated via UPDATE_SCHEMA=1.
* fix(transport): downgrade idle timeout log from error to debug
Idle keep-alive timeout is normal zombie-session cleanup, not a transport failure.
Route it through a dedicated WorkerQuitReason::IdleTimeout variant.
Log it at debug level instead of treating it as a fatal error.
Remove the unused LocalSessionWorkerError::KeepAliveTimeout variant.
Closes#817
* fix(session): tolerate dead worker in close_session
Swallow SessionServiceTerminated in close_session when the worker has already exited.
This prevents a spurious ERROR log during the post-exit cleanup path in
spawn_session_worker.
* fix(transport): address PR review feedback
- deprecate KeepAliveTimeout
- harden tests
* feat(router): support runtime disabling of tools
Add methods to disable/enable tools at runtime.
Disabled tools are hidden from listing, lookup,
and execution, including in composed routers.
Closes#477
* fix(router): simplify disable tool api
* feat(router): auto-send tools/list_changed on disable/enable
* refactor(router): simplify disable_route and notifier call
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.
* fix: include http_request_id in request-wise priming event IDs
* refactor: use Option::into_iter and usize::from for priming
* fix: retain event cache for completed request-wise channels
* fix: track completed_at for cache eviction and resume
* fix: log resume failures at warn level
* test: add completed_cache_ttl eviction test
* fix: return empty stream on failed resume
* test: add resume after completion test
* fix(http): reduce latency on subsequent StreamableHttp calls
* refactor: rely on stream drain for connection reuse
* refactor: clean up comments and naming
* fix: restore pool_max_idle_per_host(0) for Linux
AuthRequiredError, InsufficientScopeError, and DynamicTransportError
were marked #[non_exhaustive] in #715/#768 but don't have constructors
usable by external crates. Add new() for the error types and
from_parts() for DynamicTransportError (the existing new() requires a
Transport type parameter, making it unusable for test fixtures).
Fixes#805
* fix(server): remove initialized notification gate to support Streamable HTTP
The server's init handshake loop fatally rejected any request arriving
before the `notifications/initialized` message. This breaks Streamable
HTTP clients where each JSON-RPC message is a separate POST with no
ordering guarantee — `tools/list` can easily arrive before `initialized`.
Remove the ~40-line wait loop and enter `serve_inner` immediately after
sending `InitializeResult`. The `initialized` notification is now
handled as a regular notification by the main service loop, matching the
TypeScript SDK behavior (validated in typescript-sdk#578).
Also remove the now-unreachable `ExpectedInitializedNotification` error
variant from `ServerInitializeError`.
Closes#783
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(server): keep ExpectedInitializedNotification as deprecated
Retain the variant for semver compatibility — removing it would be a
breaking change caught by cargo-semver-checks. Mark it deprecated with
a note that it is never constructed and will be removed in a future
major release.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Anar Azadaliyev <anar.azadaliye@gmail.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* feat(macros): auto-generate get_info and default router
* docs: simplify examples and docs with new defaults
* feat(macros): add tool_router(server_handler) to elide separate #[tool_handler] impl
* docs: add Tools section to README and simplify calculator examples with server_handler
* feat(transport): add which_command for cross-platform executable resolution
Adds a `which_command()` helper that resolves executable paths via the
`which` crate before constructing a `tokio::process::Command`. This fixes
Windows failures where `.cmd` shim scripts (e.g. `npx.cmd`) are not
found by `Command::new()` without a fully-qualified path.
Closes#456
* refactor(transport): move which_command behind opt-in feature flag
Address review feedback: the `which` dependency is now gated behind a
separate `which-command` feature flag instead of being bundled into
`transport-child-process`. Users on Linux/macOS who don't need
cross-platform executable resolution no longer pull in the extra crate.
Also fixes the doc example import path to use the re-exported
`rmcp::transport::which_command`.
The `local` feature relaxes Send+Sync bounds, which causes items
gated behind `cfg(not(feature = "local"))` to be excluded when
docs.rs builds with all-features. Replace `all-features = true`
with an explicit feature list that omits `local`.
Signed-off-by: majiayu000 <1835304752@qq.com>
StoredCredentials is #[non_exhaustive] but has no constructor, making
it impossible for external crates implementing CredentialStore to
construct instances without a serde roundtrip workaround. Add a new()
constructor matching the pattern used for other #[non_exhaustive]
types in this crate.
Fixes#777
* feat: add theme field to Icon
* fix: update IconThem crates/rmcp/src/model.rs (non_exhaustive)
Co-authored-by: Dale Seo <5466341+DaleSeo@users.noreply.github.com>
* fix: update IconThem crates/rmcp/src/model.rs (eq, hash)
Co-authored-by: Dale Seo <5466341+DaleSeo@users.noreply.github.com>
* fix: update docs with full descriptions of theme from mcp spec
---------
Co-authored-by: Dale Seo <5466341+DaleSeo@users.noreply.github.com>
* feat(transport): add Unix domain socket client for streamable HTTP
MCP hosts in Kubernetes environments with Envoy sidecars need to route
HTTP through Unix domain sockets because DNS-based URIs only resolve
via the proxy. Adds UnixSocketHttpClient implementing StreamableHttpClient
using hyper over tokio::net::UnixStream, gated behind the
transport-streamable-http-client-unix-socket feature.
Also extracts RESERVED_HEADERS, extract_scope_from_header, and
validate_custom_header into common/http_header.rs to share header
validation logic between the reqwest and unix socket implementations.
* fix(transport): address review feedback for unix socket transport
- Document one-connection-per-request behavior on UnixSocketHttpClient
- Reject empty socket paths and bare '@' in constructor with assert
- Add explicit dep:http to unix-socket feature for self-documenting deps
- Document MCP-Protocol-Version exception on RESERVED_HEADERS constant
- Fix test catch-all to echo request id instead of hardcoding 1
- Remove leftover sleep(100ms) in test_unix_socket_custom_headers
- Add blank line before macro comment in Cargo.toml
* fix(transport): fix CI failures for unix socket transport
- Use std::io::Error::other() instead of Error::new(ErrorKind::Other)
to satisfy clippy::io_other_error on newer nightly
- Use #[tokio::test(flavor = "current_thread")] for unix socket tests
since axum's serve(UnixListener) requires spawn_local
- Gate validate_custom_header behind client-side-sse feature since it
references http::HeaderName which isn't available with default features
* fix(transport): fix CI failures for unix socket transport
axum::serve(UnixListener) uses spawn_local on Linux, which panics
outside a LocalSet. Replace with manual hyper HTTP/1.1 server that
accepts connections directly from the UnixListener, avoiding the
spawn_local requirement entirely.
* fix(transport): skip unix socket tests when local feature is enabled
The local feature causes ().serve(transport) to use spawn_local, which
requires a LocalSet. Gate the integration tests with not(feature = "local")
to match every other integration test in the repo.
