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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the bar is lower. The description adds genuinely new context: which run states are eligible (queued/running) and the required OAuth scope, both of which affect whether the call will succeed.

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, front-loaded sentences with no filler; the action and its prerequisite come first. It is efficient, though arguably too terse for a destructive mutation.

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 destructive mutation with annotations covering the safety profile and no output schema, the essentials are present. However, it says nothing about idempotency, effect on the run's jobs, or the meaning of two of the three parameters, leaving real gaps.

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 only 33% – run_id is documented with a useful leading-hex-part hint, but owner and repo carry no meaning in either schema or description. The description's mention of 'repo scope' refers to OAuth scope, not the repo parameter, so it does not compensate for the gap.

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) plus the resource (workflow run) and narrows the scope to 'queued/running', which distinguishes it from read-oriented siblings like get_workflow_run and get_workflow_logs. It does not name any sibling explicitly, so it stops short of a 5.

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 only guidance is a prerequisite ('Requires repo scope'), which tells the agent about auth but not when to choose this over alternatives or when not to use it. Usage is implied by the verb rather than stated.

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