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

The description discloses the verification mechanism (fetches the URL and confirms the token) and the consequence (earning a trusted badge), adding context beyond what annotations provide. It also notes the dependency on the api_key from register_server. These details are useful and do not contradict any annotations, though failure behavior is not described.

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 a few sentences long and front-loads the core purpose before explaining the mechanism and benefits. The sentence about buyers filtering verified sellers is somewhat promotional but still contributes to understanding the value. Overall, it is concise and structured effectively.

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?

The tool is simple (one parameter) and the description covers the verification process and outcome. However, there is no output schema, and the description does not mention what happens on failure or the structure of the response. Additionally, the mismatch between the schema (api_key not required) and the description (requires api_key) leaves an incomplete and slightly confusing picture.

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 already describes api_key as 'Your seller key.' The description adds that the key comes from register_server, providing extra context. However, the description says it is required while the schema lists it as not required, causing slight confusion. Despite this, the added context is helpful.

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 clearly states the tool's purpose: proving ownership of a listed server to earn a trusted badge. It uses a specific verb ('Prove') with a specific resource ('ownership of the server they listed'), and it distinguishes from sibling tools by focusing on verification rather than earnings or listing.

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 provides explicit guidance on when to use the tool: 'Use after they have published their verification token at /.well-known/paygate-verify on the server's domain.' It also mentions a prerequisite ('Requires the api_key from register_server'). However, it does not mention when not to use the tool or suggest alternatives, so it doesn't fully meet the 'when-not/alternatives' criterion.

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