cancel_jobCancel a queued job before it starts; jobs that are already running cannot be cancelled.
Cancel a job that is still queued. A job that already started cannot be cancelled.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered. The description adds the real behavioral constraint that cancellation is only possible pre-start, which is not derivable from annotations. It does not say whether cancelling a started job errors or silently no-ops.
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 with zero filler, and the actionable precondition is placed first. Nothing repeats the title or the schema.
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?
For a single-parameter mutation with full annotation coverage and no output schema, the description supplies the one non-obvious fact an agent needs: queued-only eligibility. Only the failure mode for an ineligible job is left unstated.
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 description coverage is 0% and the sole parameter is bare 'id' with no type context beyond string. The description implies it is a job identifier via 'a job', but adds no format, source, or lookup guidance beyond that inference.
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 and resource ('Cancel a job') plus a scope qualifier ('still queued'), which separates it from read-oriented siblings like get_job and list_jobs. It never names a sibling explicitly, so differentiation is inferred rather than stated.
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 when-it-works condition (job is still queued) and a when-it-does-not (job already started). It stops short of saying what to do instead when the job has started, so there is no true alternative path named.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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