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

Even with annotations (readOnly, idempotent, etc.), the description adds significant behavioral detail: the result is 'bounded,' contacts are not followed, JavaScript is not executed, and caching behavior is explained. This goes well beyond the annotations and gives the agent a clear model of side effects and limits.

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 very compact: three sentences, front-loaded with the core action, then constraints and parameter guidance. No filler or redundancy. Every sentence contributes.

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 the tool's simplicity, the presence of an output schema, and strong annotations, this description is fully complete. It covers purpose, constraints, and both parameters' intended usage with no gaps.

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%, providing baseline 3. The description adds value by explaining the semantic difference of 'fresh=false' (cache reuse) vs 'fresh=true' (new upstream fetch), which is not obvious from the schema's type/default. This nudges the score to 4.

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 uses a specific verb ('Fetch') and resource ('public security.txt text'), and includes a key differentiator: 'without following contacts.' This clearly distinguishes it from sibling tools like web.site.robots or web.site.sitemaps.

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?

Explicitly states constraints: 'Use only for public HTTP(S) resources' and lists two limitations (no JavaScript, no access control bypass). Also provides clear guidance on the 'fresh' parameter. However, it does not name an alternative tool, so it stops short of a full 5.

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