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

Annotations only declare readOnlyHint and openWorldHint, so the description adds real value: it discloses SSRF-guarded redirect following, the exact grading rubric, the return payload (score, failed checks with severity, all header values), and per-call pricing ($0.005 USDC on Base via x402). The payment requirement is especially important behavioral context not in annotations. It stops short of noting rate limits or failure behavior for unreachable sites.

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?

A single dense but front-loaded sentence that enumerates the graded checks, the outputs, and the price with no filler. Every clause maps to something an agent needs (scope, redirects, output, cost).

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 one-parameter read tool with no output schema, the description fully compensates by naming the return payload (score, failed checks with severity, all header values) and the payment model. Combined with readOnly/openWorld annotations, an agent has everything needed to call it correctly.

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?

Only one parameter with 100% schema description coverage ('http(s) URL of a public site'), so the schema already carries its meaning. The description reinforces that the target must be a public site with redirects followed, but adds no format or validation detail beyond the schema. Baseline 3 is appropriate.

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 ('Website security-headers audit') plus the exact scope of the audit (HSTS, CSP, clickjacking, nosniff, Referrer-Policy, Permissions-Policy, COOP, version-leaking headers, cookie flags) and the output shape (A–F grade). This is clearly distinguishable from siblings like web_extract or web_brand, which do not grade headers.

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?

Usage is implied by the narrow scope: audit a public site's security headers. It clarifies it follows redirects and that the URL must be a public http(s) site, but gives no explicit when-to-use versus alternatives and no when-not-to-use guidance (e.g. private/internal hosts).

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