Cancel a job

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

The description adds rich behavioral details beyond the annotations: queued jobs are cancelled immediately, running jobs are gracefully requested to stop, the worker terminates the ffmpeg subprocess within about a second, it works even if the job was started by a different process like the local UI, and finished jobs are untouched. This provides a clear picture of side effects and operational behavior, which the annotations (readOnlyHint false, destructiveHint false) do not convey.

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?

The description is three sentences, front-loaded with the core action. The second sentence provides necessary nuanced behavior for running jobs, and the third covers the edge case of finished jobs. Every sentence adds value and there is no waste or redundancy.

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?

Given the tool's simplicity (one parameter) and the presence of an output schema, the description is complete. It covers all relevant job states (queued, running, finished) and even mentions cross-process behavior. There is no missing context that would confuse an agent about when or how to invoke this tool.

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?

The input schema has full coverage (100%) for the single parameter job_id, with description 'Job id returned when the work was queued.' The tool description does not add any additional parameter semantics, but the schema already provides sufficient meaning. Thus the baseline of 3 applies without needing extra compensation.

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?

The description clearly states the tool's function: 'Stop a queued or running job.' The verb 'stop' (or cancel) plus the resource 'job' is specific and unambiguous. It distinguishes itself from sibling tools like job_status or job_result, which are about querying rather than cancelling, and there is no other cancellation tool among the siblings.

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?

The description provides clear context on when to use the tool (for queued or running jobs) and explicit when-not guidance ('Jobs that already finished are left alone'). It does not name alternative tools, but the distinction is clear enough given that no other sibling tool performs cancellation, so the exclusion of finished jobs effectively covers when not to use it.

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