Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the mutation/safety profile is covered. The description adds genuinely new behavioral context: this is a partial (patch) update where omitted fields are preserved and supplied fields are overwritten, which is not derivable from the annotations. It stops short of stating permissions or what a no-match id returns.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three tight sentences, front-loaded with the action, then the patch semantics, then the sibling routing and precondition. Nothing is redundant or padded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present, return values need no explanation, and the annotations carry the safety profile. The description covers action, patch semantics, precondition, and sibling routing; only minor gaps remain (permission requirements, error behavior on a bad id).

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 83% (high), so the baseline is 3; the description clears that by explaining the replace-on-supply / preserve-on-omit semantics that the schema does not state for any of the six parameters. It does not mention 'context' or restate the id source, both of which the schema already documents.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb on a specific resource ('Change an action item') and enumerates the mutable fields (wording, owner, due date, priority). It explicitly distinguishes itself from the complete_task sibling, so an agent can route without opening a schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Names the alternative tool for a different intent ('Use complete_task to mark it done') and adds a real pre-call condition ('Call it only when the user asked for this change'). It does not say when not to use it for other conflicting cases, but the routing guidance is clear and actionable.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.