feat(sequential-thinking): add tool annotations#3534
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olaservo merged 1 commit intomodelcontextprotocol:mainfrom Mar 15, 2026
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Add readOnlyHint, destructiveHint, idempotentHint, and openWorldHint annotations to the sequentialthinking tool, consistent with how server-filesystem annotates its tools. The tool is pure computation (readOnly), produces deterministic structure for the same input (idempotent), and makes no external calls (not openWorld). Fixes modelcontextprotocol#3403
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Clean, well-scoped addition of tool annotations to the sequential-thinking server. All four annotation values are semantically correct:
readOnlyHint: true— the tool doesn't modify any external environment (files, network, DB). The in-process state accumulation (thoughtHistory, branches) is an implementation detail, not an environmental side effect in the MCP sense.openWorldHint: false— no network calls or external interactions.destructiveHint: false/idempotentHint: true— redundant per the MCP spec whenreadOnlyHintistrue, but not harmful. The filesystem server takes the terser approach of omitting these for read-only tools, but being explicit is a valid stylistic choice.
LGTM — thanks for the contribution @nielskaspers!
Reviewed with the assistance of Claude Code (claude-opus-4-6). Annotation semantics verified against the MCP specification and sequential-thinking source code.
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…#3534) feat(sequential-thinking): add tool annotations Adds MCP ToolAnnotations (readOnlyHint, destructiveHint, idempotentHint, openWorldHint) to the sequential-thinking tool, bringing it in line with the annotation pattern established by the filesystem server. Fixes modelcontextprotocol#3403
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Summary
Adds tool annotations to the
sequentialthinkingtool, matching the pattern established by server-filesystem. This is the last unannotated reference server with a single tool.Issue
Fixes #3403
Changes
readOnlyHint: true— pure computation, no state persisted or files writtendestructiveHint: false— no data is modified or deletedidempotentHint: true— same input produces same reasoning structureopenWorldHint: false— no external API calls or network accessTesting