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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the destructive nature is known; the description adds a real precondition beyond that ('open frozen job only'), telling the agent the tool will fail on closed jobs. It does not state whether cancellation is reversible or what a successful cancel leaves behind.

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 short sentences, zero filler, with the action and its scope stated first and the exclusion immediately after. Nothing is over-explained.

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?

An output schema exists, so return values need not be described, and the annotations carry the safety profile. What remains thin is the failure mode — behavior on a non-open or already-cancelled job — and any description of the sole parameter.

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?

One required parameter with 0% schema description coverage, so the description was the only place to explain it — yet jobId is never mentioned. The agent gets no hint about format, where to obtain the job ID, or whether it accepts an external identifier.

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 (cancel) and resource (an open frozen job), plus an explicit boundary against skill-loop runs. The 'Completion-loop:' prefix and the term 'frozen' are unexplained jargon, but the core action is unambiguous.

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?

Gives a clear exclusion — do not use for skill-loop runs, use the run lifecycle instead — which routes the agent away from a wrong path. It does not cover when to prefer this over job_approve/job_status or what to do if the job is not open, but the primary disambiguation is present.

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