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

Beyond the annotations (destructiveHint, idempotentHint), the description discloses the refund of held coins in full and the fact that the provider is never notified, so an in-flight result is silently discarded. Those side effects and the paid-resource implications are exactly the behavioral context annotations cannot convey.

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?

Three short sentences with zero filler; the core action is front-loaded and each following sentence adds a distinct, load-bearing fact (refund, provider silence, ineligibility of finished jobs).

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 cancellation tool with no output schema, the description covers the eligibility rule, the cost outcome, and the side effect of discarding in-flight results. Nothing an agent needs to call it correctly is missing.

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 100% and the single 'id' parameter is documented in the schema as coming 'from generate or list_generations'. The prose adds no additional meaning about the parameter, so the baseline 3 applies.

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?

The description opens with a specific verb and resource ('Cancel a queued or running generation') and immediately scopes it to two lifecycle states. No sibling tool shares this resource, so an agent can pick it without ambiguity.

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?

It states both the positive condition (queued or running) and an explicit exclusion ('A finished generation cannot be canceled'), which is exactly the guidance an agent needs. It stops short of naming an alternative tool, though no sibling offers the same cancel capability.

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