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

Annotations already convey read-only, idempotent, non-destructive behavior. The description adds meaningful behavioral context beyond annotations: it does not execute JavaScript or bypass access controls, and it explains the caching behavior tied to the 'fresh' parameter. These details help the agent understand real-world side effects and limitations.

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 three sentences, front-loaded with the core purpose. Every sentence adds distinct value: what it assesses, usage constraints/limitations, and parameter-specific caching advice. There is no fluff or redundancy.

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?

Given that an output schema exists, the description covers the essentials: what the tool does, when it can be used (public HTTP(S) only), key behavioral limitations, and caching semantics. This is sufficient for an agent to decide when to invoke the tool and what to expect. No critical information 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 description coverage is 100%, so the description is not required to explain parameters. It does restate the 'url' and 'fresh' guidance, but largely repeats what the schema already says. The only marginal addition is the rationale that fresh=false is 'cheaper for the origin,' but this is also present in the schema's fresh description. Thus 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 clearly states the tool assesses CSP, CORS, cross-origin policy, and mixed-content signals, which is a specific verb+resource pairing. This distinguishes it from sibling tools like web.url.headers or web.url.security_headers, and the limitation clause ('does not execute JavaScript or bypass access controls') further disambiguates its scope.

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 provides explicit usage conditions: 'Use only for public HTTP(S) resources' and caching guidance ('Keep fresh=false... set fresh=true only when a new upstream fetch is required'). However, it does not explicitly name alternative tools or state when to prefer this over a sibling, so it lacks the full when/when-not structure of a 5.

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