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

Annotations already establish readOnly, idempotent, and non-destructive behavior. The description adds valuable behavioral context beyond the annotations: the call makes a live HTTP request (network dependency), costs $0.03 per call, and returns a specific shape (pass bool and findings[] with id/severity/detail). This is more than the annotations alone provide.

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 description is a single dense sentence front-loaded with the key scope, followed by an exclusion, cost, and return summary. Every element earns its place; there is no filler or repetition of schema data.

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?

With an output schema present and one fully documented parameter, the description is complete for practical use. It tells the agent exactly what is checked, what is not, what it costs, and what the response contains, leaving no meaningful gap for correct invocation.

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?

The schema already fully documents the single parameter with description and format, and schema coverage is 100%, so the baseline of 3 applies. The description adds no additional semantic detail about the url parameter beyond what the schema provides, but it doesn't need to.

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 action verb with a clear resource: auditing security headers from a live HTTP response. It enumerates the exact checks (HTTPS, HSTS, CSP, X-Content-Type-Options, clickjacking, Referrer-Policy, CORS) and explicitly excludes TLS/cipher scans and penetration tests, making it easy to distinguish from the other audit siblings.

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 description clearly says what the tool covers and explicitly states what it does not cover ('not a TLS/cipher scan or a penetration test'), which is useful when-routing guidance. It does not name sibling tools directly, but the listed checks leave little doubt about when this should be selected over audit_performance, audit_seo, or audit_wcag.

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