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

With only generic annotations present, the description carries the behavioral burden and explains the unusual payment flow thoroughly: results come in the same response once payment settles, there is no separate read-back call, charges occur only on success, and the receipt is returned in _meta['x402/payment-response']. No contradiction with the annotations.

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 core usage and payment instructions are front-loaded, but the description is longer than needed. The complaints/questions/feedback sentence and the note that 'every report is read and analysed daily; there is no individual reply' do not help an agent invoke the tool correctly and could be omitted without losing required context.

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 has a complex x402 payment flow and no output schema, yet the description covers the two-step payable call, the free-failure mode, response content, receipt location, and the fact that no account or API key is needed. An agent has enough information to make the call and handle the expected price/refusal flow.

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% for the single url parameter, including format and length constraints, so the schema already documents the parameter well. The description adds domain context about risk feeds and payment, but no additional parameter-level semantic detail beyond 'URL'.

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 and object: 'check a URL against public risk feeds' and enumerates the outputs: verdict, score, and reasons. This clearly distinguishes it from sibling tools like check_address, which operates on addresses.

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 gives exact sequential usage: call once without payment to receive the x402 price, then call again with a signed payment in _meta['x402/payment']. It also defines when the request is refused for free via CHECK_SOURCES_UNAVAILABLE. It does not explicitly name alternatives or exclusions, but the URL-risk context makes appropriate use clear.

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