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

Annotations already cover readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint. The description adds meaningful context: free tier, rate limit, exact scope (homepage meta/OG/canonical, security headers, HTTPS, up to 20 broken-link checks), and routes to the paid alternative. It does not describe return format or error behavior, but the annotations carry the safety profile.

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?

Front-loads the free/rate-limit signal, then the purpose, then the paid alternative. Two compact sentences with no wasted words.

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?

No output schema exists, so the description must convey what the tool returns; it lists the checked areas (meta/OG/canonical, security headers, HTTPS, link breakage). It stops short of describing return structure or failure modes, but this is sufficient for a simple one-parameter check tool.

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 single url parameter is fully documented in the schema. The description adds no syntax or format details beyond what the schema provides, so baseline 3 is appropriate when the schema does the heavy lifting.

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 ('check') and resource ('one public website'), enumerates the exact checks performed, and explicitly names the sibling website_audit as the deeper paid alternative. An agent can distinguish it from siblings without opening the schema.

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 the free rate limit (10 calls/hour per IP) and directs deeper 3-page audits with leaked-key scanning to website_audit (paid). It gives both the condition for using this tool and the alternative when that condition is not met.

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