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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the pricing ($0.01) and the concrete GET route, though the 402/payment handshake itself is documented in the schema rather than here.

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 compact sentences with no waste; the what and the cost are front-loaded. The telegraphic style is efficient but slightly at the expense of readability.

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 simple one-required-parameter read-only scoring tool with no output schema, the description covers what is measured, the 0–10 output scale, and the per-call price. Little more is needed, though a note on whether a full breakdown is returned would round it out.

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%, including a detailed explanation of the optional payment proof parameter and the required https URL. The description adds only the route showing how url is passed; baseline 3 is appropriate when the schema carries the parameter burden.

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 — scoring security headers for a URL — and enumerates the dimensions checked (CSP, HSTS, framing, cookies, TLS), which distinguishes it from sibling health/vuln checks like check_cves and get_site_health. It stops short of explicitly naming which sibling to use instead.

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?

No statement of when to use this versus check_cves, get_site_health, or check_webmcp, and no prerequisites or exclusions. Usage is only implied by the task description itself.

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