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

With no annotations, the description carries the full burden and does well: it discloses the HTTP method, redirect ceiling, timeout, and crucially that the body is never read, which tells the agent this is a lightweight read with no content side effects. It omits auth/rate-limit behavior on the target, which keeps it from a 5.

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?

Two sentences, densely packed with distinct facts (method, redirects, timeout, body handling, grading scale, return fields) and zero filler. The operation and its constraints are front-loaded before the return-value detail.

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 enumerating what comes back: score, present/missing headers, per-header findings with fix values, and cookie flag issues. That is complete enough to call the tool correctly; only the absence of any note on failure modes (unreachable host, non-2xx, private URL rejection) leaves a small gap.

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 100% and the single parameter is fully documented in the schema ('Public http or https URL to grade, e.g. https://github.com'), including length bounds. The description's 'public http(s) URL' phrasing merely restates the schema rather than adding new constraint detail, so the baseline 3 applies.

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 opens with a specific verb+resource pair ('Fetches a public http(s) URL ... and grades its security headers A+ to F') and states the exact artifact produced, including the grading scale. There are no siblings to differentiate from, and the purpose is unambiguous from the first sentence.

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?

It gives concrete operating context: GET method, up to 5 redirects, 10s timeout, body never read, and the URL must be public http(s). What's missing is any statement of when not to use it (e.g. internal/private hosts are rejected, non-HTML resources) — the 'public' qualifier hints at an exclusion but never names it explicitly.

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