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

Annotations already declare read-only, open-world, idempotent, non-destructive behavior. The description adds critical behavioral context beyond annotations: the x402 payment model ($0.008 USDC per successful call), 'Low Bazaar crowding', and an alternative HTTPS endpoint. These details materially affect how an agent invokes the tool.

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 purpose and key caveats are front-loaded, and the description is packed without redundancy. The price and alternative endpoint are useful, though the compact list of factors feels slightly dense; every sentence still carries information relevant to invocation.

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?

Given one parameter, no output schema, and annotations covering safety, the description does enough: it explains what the score is based on, that output is scored signals rather than a verdict, and payment requirements. It could go further in describing the returned signal structure, but no output schema exists and the current information is sufficient for correct invocation.

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 fully documents the single 'url' parameter at 100% coverage, so the baseline is 3. The description does not add any syntax, format, or edge-case guidance for the parameter beyond what the schema provides.

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 ('score') and resource ('URL/domain') and lists the factors that feed the heuristic. It distinguishes itself from generic domain tools by focusing on phishing likelihood and clarifying output is 'scored signals — not a verdict', but it does not explicitly name or differentiate from siblings like domain_intel or ssl_cert_info.

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 no explicit guidance on when to use this tool versus alternatives. The phrase 'not a verdict' hints at a usage caveat, but there is no statement of context, prerequisites, or sibling alternatives that would help an agent choose between this and related tools.

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