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

Annotations already declare readOnly, idempotent, closed-world, non-destructive, so the safety profile is covered. The description adds useful scope context by clarifying it performs no checking and is purely explanatory, though it says nothing about the shape of the explanation returned.

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 sentences: the capability and its values come first, then the usage triggers and the negative scope. No filler and nothing buried.

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 one-parameter, read-only lookup with full annotation coverage and no output schema, the description covers what the tool does, when to call it, valid values, and what it does not do. Nothing needed for 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 description coverage is 100% and the enum already constrains the single parameter, so the baseline is 3. The description does add a light gloss ('quality (page health)') and lists the valid values, but that largely duplicates the enum.

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?

Specific verb (explains) plus a defined resource (one of six Sitecomb areas) and it enumerates all six ids inline, so the agent knows exactly what comes back conceptually. The closing line rules out the most likely confusion with the sibling check_website.

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 gives explicit trigger conditions: when someone asks what Sitecomb checks, or when an area is named in a check_website result. It also states a negative case ('It doesn't check any website'), which routes the agent to check_website when actual scanning is needed.

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