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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so the safety profile is covered structurally. The description adds the meaningful constraint that only in-progress runs are cancellable, but says nothing about the effect on messages already queued or sent, or whether cancellation is immediate or graceful.

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?

A single six-word sentence with the action and the state constraint front-loaded. There is no filler, though the brevity is close to the point of under-specification.

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, idempotent mutation with a fully documented two-parameter schema and no output schema, the essentials are covered. The remaining gap is what cancellation actually does to in-flight or already-sent messages, which an agent may need to set expectations before calling.

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% with both parameters (id, run_id) documented as automation id and run id. The description adds no additional meaning about the relationship between the two identifiers, so it sits at the baseline where the schema does the work.

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 run) with a scoping qualifier (in progress). It does not distinguish itself from the similarly named siblings cancel_batch, cancel_scheduled_message, or pause_automation, so an agent must infer that this targets an automation run rather than a batch or a scheduled message.

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?

'In progress' implies the precondition that the run must still be active, which is the main trigger condition. However, there is no explicit statement of when to prefer this over pause_automation or how to handle a run that has already finished, so usage is only implied.

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