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

Beyond the sparse annotations (not read-only, not destructive, not open-world), the description discloses substantial behavior: charging only on success, refusing with CHECK_SOURCES_UNAVAILABLE rather than returning an unsourced verdict, returning payment receipt in _meta, and requiring no authentication. This is exactly the kind of non-obvious behavioral context an agent needs.

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 front-loaded with the paid nature, purpose, and output, and the x402 flow is explained efficiently. However, the closing feedback paragraph ('Complaints, questions, quote requests...') is unrelated to tool invocation and adds noise. The description would be stronger if that promotional content were removed or moved to a non-description channel.

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?

Even with no output schema, the description tells the agent what to expect (verdict, score, reasons), how to discover the price via PaymentRequired, how to complete the call with a signed payment, where the receipt appears, and what happens when sources are unavailable. For a complex paid x402 tool, this is a complete and self-sufficient explanation.

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 input schema already documents both parameters (address and chain) at 100% coverage, so the description is not required to repeat them. It adds some payment-related context about Base and Solana USDC, but that is settlement currency context rather than parameter semantics. A baseline of 3 is appropriate given full schema coverage.

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 resource: 'check an EVM address against public risk feeds' and names the returned artifacts (verdict, score, reasons). It also distinguishes this from URL-checking by limiting scope to EVM addresses, and the 'no separate read-back call' detail sharpens the tool's identity.

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 clear operational context: it is paid via x402, the first unpaid call returns a price, and the second call completes with a signed payment in _meta['x402/payment']. It also clarifies no account or API key is needed. However, it does not explicitly state when to prefer this over sibling tools like check_url or when not to use it.

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