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

With readOnlyHint and openWorldHint already set, the description adds genuinely useful context: the returned fields, the A/B/C/F grading scheme, the 3-credit cost, and that schema-invalid input is rejected before billing. It does not say whether redirects are followed or whether the front page must serve HTTPS, which are the remaining behavioral unknowns.

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 scope are front-loaded, followed by the return shape and billing note. Dense but every sentence carries useful information; no filler.

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 single-parameter read-only tool with no output schema, the description covers purpose, return object, grading, and cost/billing behavior well. Minor gaps remain around redirect handling and what exactly constitutes the 'front page', but nothing critical to correct invocation is missing.

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 100%, so the domain parameter's constraints (length, IP literal and private suffix rejection) are fully documented in the schema. The description adds only the implicit 'front page of that domain' framing and no syntax or format detail beyond the schema, so 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?

States a specific verb (audit/sends) and resource (security headers on a site's HTTPS front page), plus the exact output shape and grade scale. An agent can distinguish it from siblings like cors-check, https-redirect, and security-txt without opening any 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?

The scope (HTTPS front page security headers) implies when it applies, but the description never names alternatives or exclusions, e.g. redirect behavior or non-header checks handled by https-redirect or cors-check. Usage is inferred rather than directed.

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