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

No annotations exist, so the description carries the full burden. It does add real behavior detail the schema cannot: SSRF-safe execution, a scored output, and a $0.001 USDC price. It omits whether the call is side-effect free in any meaningful sense, what happens with bad input, whether both `url` and `domain` may be supplied, and what the score range or failure response looks like.

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 capability and header list, and the usage example is compact. But the trailing price/sibling promo block (four priced cross-references) is dense marketing prose that dilutes the operational content an agent needs, and the abbreviation-heavy header list (XFO, XCTO) is terse without being explanatory.

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 two-parameter, no-output-schema, no-annotation tool the description covers purpose, input examples, safety posture, and cost. It falls short on the things that most affect correct invocation: parameter requiredness/precedence between `url` and `domain`, and any hint of the response shape beyond the word "score".

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 0%, and the two params are also non-required, so the description should compensate. It partially does by giving concrete shapes (`{url:"https://example.com"}` vs `{domain:"example.com"}`), which clarifies URL-with-scheme versus bare-domain input. It still leaves the critical ambiguity unresolved: are the two alternatives, is either mandatory, and which wins if both are present.

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?

Names a specific verb and resource ("HTTP security headers audit") and enumerates exactly what is checked (HSTS/CSP/XFO/XCTO/Referrer/Permissions/COOP/CORP/COEP) plus a score. The "Not a pen-test" line and the adjacent sibling list (redirects, meta, DNS, /check) let an agent separate this from url_redirects, page_meta, and dns_lookup without opening a 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?

Provides one explicit exclusion ("Not a pen-test") and points to related tools by name and price, which gives context about what this tool does *not* cover. However, it never states when to pick this versus the listed neighbours — e.g. no rule saying "use /redirects if you only need the redirect chain" — so routing must be inferred.

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