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

Beyond the destructiveHint/idempotentHint annotations, the description discloses the authorization model for In review tasks (only proposer, the proposer's person, or the decider may withdraw) and the exact failure mode (REVIEW_NOT_YOURS with details.reviewer). It also tells the agent the action is reversible via reopen, which the annotations cannot express.

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?

Two front-loaded clauses: the core action and scope first, then the special-case permission rule. It is dense with jargon ('the proposer's person') but every sentence carries decision-relevant information.

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 a rich output schema and full annotation coverage, the remaining burden is the permission semantics, and the description handles the non-obvious In review case and its error code explicitly. Nothing an agent needs to call this correctly is absent.

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 100%, so id, why, and reason are already fully documented in the schema, including the one-sentence and 300-character constraints on why. The description only restates that reason is optional, adding no syntax or format detail beyond the structured fields.

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?

Specific verb ('Cancel') plus resource ('task') and an explicit scope: only To do, Doing or In review tasks. That scope distinguishes it from task_complete and task_stop implicitly, though it never names a sibling outright.

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?

It states the selection condition ('a task that will not be done') and the reversibility path ('it can be reopened'), which is the key when-to-use signal versus completing or stopping. There is no explicit mention of when NOT to use it or of the alternate tools by name.

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