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

Annotations already declare idempotent and non-destructive hints. The description adds valuable behavioral context about billing and result retention: already-verified addresses remain billed and in results, while unprocessed ones are never charged. This goes beyond what annotations convey and helps the agent understand side effects.

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?

The description is two sentences with no wasted words. The primary purpose is front-loaded, and the second sentence concisely explains the billing and results consequences. Every sentence earns its place.

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 simple one-parameter tool with no output schema and annotations covering idempotency and non-destructiveness, the description provides the necessary purpose and side effects. It does not mention response format, but that is not critical for a cancellation action.

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?

The schema covers the only parameter (jobId) with a minimal description 'The job ID', so baseline is 3. The tool description adds no extra information about the parameter itself, but the parameter is self-explanatory given the tool name.

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 states a specific verb ('Stops') and resource ('a running verification job'), clearly distinguishing it from creation, listing, or retrieval of verification jobs. The billing note further clarifies the scope of action, making the purpose 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 implies the tool is for stopping a running verification job, which is clear context for when to use it. It does not explicitly mention alternatives or exclusions, but the sibling context and action verb make the use case obvious.

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