check_price

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

With no annotations, the description carries the full burden and does well: it discloses the no-payment guarantee, the trigger condition (HTTP 402), and what gets reported (price, recipient, chain, spending-limit check). The remaining gap is behavior for non-402 responses (e.g., a 200 that is not paywalled) and any auth/rate-limit constraints, which are left unstated.

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 tightly written sentences, front-loaded with the core purpose and the key constraint ('WITHOUT paying'), followed by behavior and routing guidance. No sentence is filler.

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 one-parameter tool with no annotations and no output schema, the description is nearly self-sufficient: it explains the trigger, the returned fields, and when to prefer the sibling. It only falls short on the non-402 return path, which an agent would otherwise have to discover empirically.

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 url parameter is already documented as http(s) in the schema. The description adds no syntax or format detail beyond what the schema provides, 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?

States a specific verb+resource ('look at what a paid resource costs') with a sharp scope qualifier ('WITHOUT paying for it'). It explicitly distinguishes itself from the sibling pay_and_fetch, so an agent can route correctly without opening any schema.

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?

Gives an explicit when-to-use rule ('before pay_and_fetch when the cost matters') and a second distinct condition ('to check whether a URL is paywalled at all'). The alternative is named, not merely implied.

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