fix(model): decode metadata-bearing input-required results affecting mrtr - #1097
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The draft permits every Result, including InputRequiredResult, to carry _meta and recommends that servers include io.modelcontextprotocol/serverInfo on every response. It also requires an InputRequiredResult to contain inputRequests or requestState so the client knows what to provide or how to resume the request. ServerResult uses untagged deserialization and attempts CallToolResult before InputRequiredResult. Because CallToolResult accepts _meta and defaults missing content to an empty list, it consumed valid input_required results carrying metadata. Unknown inputRequests and requestState fields were then discarded, leaving clients without the information needed to continue. Reject resultType input_required when deserializing CallToolResult so Serde proceeds to the InputRequiredResult variant. Add regression coverage proving that inputRequests, requestState, and serverInfo metadata are preserved. Spec: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/41d9e938e9a9edf23a69429be180cad172e00f4e/schema/draft/schema.ts#L137-L151 https://github.com/modelcontextprotocol/modelcontextprotocol/blob/41d9e938e9a9edf23a69429be180cad172e00f4e/schema/draft/schema.ts#L198-L224 https://github.com/modelcontextprotocol/modelcontextprotocol/blob/41d9e938e9a9edf23a69429be180cad172e00f4e/schema/draft/schema.ts#L541-L565 Signed-off-by: Filinto Duran <1373693+filintod@users.noreply.github.com>
DaleSeo
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Jul 30, 2026
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crates/rmcp/src/model.rs
…ng that at least one of inputRequest or requestState is present Signed-off-by: Filinto Duran <1373693+filintod@users.noreply.github.com>
DaleSeo
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Bump to latest stable release https://github.com/modelcontextprotocol/rust-sdk/releases/tag/rmcp-v3.1.0 ``` Added classify authorization-required errors (modelcontextprotocol/rust-sdk#1056) add strict stateless protocol metadata validation (modelcontextprotocol/rust-sdk#1091) SEP-2260 stream-based enforcement of client receive-side request association (modelcontextprotocol/rust-sdk#1055) Fixed (model) decode metadata-bearing input-required results affecting mrtr (modelcontextprotocol/rust-sdk#1097) require metadata for modern HTTP requests (modelcontextprotocol/rust-sdk#1089) honor supported_protocol_versions when negotiating initialize (modelcontextprotocol/rust-sdk#1093) Other document the ping utility with examples (modelcontextprotocol/rust-sdk#1106) complete Tier 1 feature docs and finalize roadmap (modelcontextprotocol/rust-sdk#1101) (conformance) meeting requirements for tier 1 (modelcontextprotocol/rust-sdk#1087) ``` Signed-off-by: Filinto Duran <1373693+filintod@users.noreply.github.com>
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The draft permits every Result, including InputRequiredResult, to carry
_meta and recommends that servers include
io.modelcontextprotocol/serverInfo on every response. It also requires
an InputRequiredResult to contain inputRequests or requestState so the
client knows what to provide or how to resume the request.
ServerResult uses untagged deserialization and attempts CallToolResult
before InputRequiredResult. Because CallToolResult accepts _meta and
defaults missing content to an empty list, it consumed valid
input_required results carrying metadata. Unknown inputRequests and
requestState fields were then discarded, leaving clients without the
information needed to continue.
Reject resultType input_required when deserializing CallToolResult so
Serde proceeds to the InputRequiredResult variant. Add regression
coverage proving that inputRequests, requestState, and serverInfo
metadata are preserved.
Spec:
Fixes #1098
Motivation and Context
Found while checking against the conformance tests and several of mrtr 2322 tests failed with missing inputRequests and/or requestState
A valid MRTR InputRequiredResult with result metadata can be misclassified as CallToolResult during untagged deserialization. The SDK then drops inputRequests and requestState, preventing clients from presenting the required elicitation or retrying with the server state.
How Has This Been Tested?
Re-run the conformance tests after building locally and tests passed
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