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

Annotations already flag destructiveHint=true, so the safety profile is covered structurally. The description adds genuine behavioral nuance: queued jobs cancel cleanly, running jobs stop only if the underlying tool supports it, and the idempotentHint=false is implicitly respected. It earns credit for explaining what cancellation actually does, though it doesn't state the resulting state of a partially-stopped job.

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 tight sentences with the core action front-loaded, the queued/running distinction in the middle, and the sibling routing at the end. Every clause carries information; no filler.

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-param mutation tool with no output schema, the description covers the action, its limits, and the alternative path. It stops short of stating the eligibility condition for 'eligible' or the post-cancel state, which would make it fully self-contained.

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?

With a single required job_id and 0% schema description coverage, the burden falls on the description, which only gestures at an 'eligible individual job' without clarifying format, eligibility criteria, or how to obtain the id. The parameter name is fairly self-evident, so this is marginal rather than absent, landing at baseline 3.

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 an eligible individual job') and explicitly scopes it against the workflow-owned case by naming the sibling cancel_workflow_run. An agent can distinguish it from cancel_workflow_run without opening either 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?

Gives explicit when-to-use ('queued jobs can be cancelled') and when-not ('Cancel workflow-owned jobs through cancel_workflow_run'), plus the running-job caveat. Routing to the correct sibling is fully specified.

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