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

Annotations already declare destructiveHint=true, and the description's 'Cancel an in-flight run' is consistent with that. It adds the endpoint version caveat ('API v2, not v1') and the HTTP route, which is useful context, but says nothing about reversibility, permissions, or the run's post-cancel state.

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 the purpose front-loaded and no wasted prose. The middle clause about API versions is slightly awkwardly worded but does not bloat the definition.

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 tool with no output schema and annotations covering the destructive profile, the description is nearly sufficient. Only post-cancellation behavior is unstated, which is a minor gap given the tool's simplicity.

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 coverage is 100% for the single run_id parameter, and the description adds no syntax or format detail beyond it. This is the expected baseline when the schema fully documents the parameter.

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 ('in-flight run'), which immediately distinguishes it from siblings like trigger_replay_run or trigger_reschedule_run without needing their schemas. It does not explicitly name an alternative sibling, but the 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?

The description gives no when-to-use or when-not-to-use guidance, no prerequisites, and does not contrast itself with siblings such as trigger_replay_run. The API-version note is a technical caveat, not usage guidance.

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