feat(server): validate accepted elicitation content against the requested schema#896
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devcrocod merged 2 commits intoJul 21, 2026
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…sted schema fixes modelcontextprotocol#895 Validate accepted form-mode content in createElicitation and fail with an INVALID_PARAMS McpException on mismatch. Absent content is validated as an empty object for `required` checks; the returned result is not modified.
rea9r
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July 20, 2026 05:18
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Validate accepted form-mode elicitation
contentagainst therequestedSchemaon the server, rejecting mismatches with anINVALID_PARAMSerror.fixes #895
Motivation and Context
createElicitationreturned accepted content to server code as-is. The specification'sform-mode security guidance says "Servers SHOULD validate received data matches the requested
schema" (2025-11-25, Form Mode Security). Comparable validation already exists in the TypeScript SDK's
elicitInputand Python'selicit_with_validationhelper. Details and design notes are in #895.How Has This Been Tested?
New unit tests for the validator and integration tests over an in-memory client–server pair.
Breaking Changes
No API changes. Behavioral note: an accepted form-mode response that does not match the requested schema now fails
createElicitationwithMcpException(INVALID_PARAMS) instead of being returned to the caller.Types of changes
Checklist