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

Goes well beyond the annotations by describing exactly what comes back (heuristic riskScore 0–100 or 'unknown', fixes, public seven-day report link), the disclaimers that scores are not safety or acceptance guarantees, and the fact that no payment or credentials are involved. It also clarifies the badge path 'reads only the existing seven-day snapshot, never runs a check,' preventing a false assumption about side effects. Nothing here contradicts readOnlyHint=false / openWorldHint=true.

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?

Front-loaded with the action and the checks performed, and most clauses carry weight (limitations, privacy warning, score caveats). The trailing CI Action URL and badge-path explanation are marginal for tool selection and add density without helping an agent decide or invoke, keeping it below 5.

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?

There is no output schema, and the description compensates by describing the return payload (riskScore range, fixes, report link) and its reliability caveats. For a one-parameter, unauthenticated lint tool it covers what an agent needs to call it correctly and interpret the result, including the key failure mode (POST-only endpoints cannot be validated).

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 0% and the only parameter is a bare `url` string with no description, so the description carries the burden — and it does: the URL must be public, HTTPS, and GET-addressable, with an explicit 'Do not submit private URLs.' It still does not clarify whether query strings/paths are accepted (the schema's example implies they are), leaving a small gap.

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 and resource: checks a public HTTPS x402 endpoint with an unpaid GET, and enumerates what it validates (v1/v2 challenge shape, payTo/asset/network syntax, price, Bazaar metadata, CORS headers). The purpose is unambiguous, but it never names the sibling it overlaps with (check_endpoint) or explicitly contrasts them, so an agent must infer the boundary.

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 real usability boundaries: 'No payment or credentials; GET cannot validate a POST-only endpoint or paid delivery. Do not submit private URLs.' It also clarifies that paid Listing Guard/monitoring links are optional and 'no paid call is made,' which implicitly separates it from listing_guard and preflight_payment. What is missing is an explicit 'use check_endpoint instead when…' routing statement.

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