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

Annotations already declare readOnly, idempotent, non-destructive, open-world behavior, so the description correctly spends its words elsewhere. It adds two things annotations cannot: the result shape (score out of 5 with pass/fail per check) and a concrete rate limit of 20 scans per hour per visitor. It does not say what happens with an unreachable or malformed URL, which is the remaining gap.

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, no filler: the first carries purpose and the enumerated checks, the second carries the return shape and the quota constraint. Front-loaded with the verb and scope, with constraints placed last where they belong.

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 scan with no output schema, the description supplies the return format (score out of 5 plus per-check pass/fail) and the rate limit, which is what an agent needs to plan calls. Only the error/edge-case behavior for invalid or unreachable URLs is unaddressed.

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 already documents both the bare-domain and full-URL forms with an example. The description adds no syntax, normalization, or constraint detail beyond the schema, so 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?

States a specific verb and resource ('Run a free 5-check scan of a website's AI/agent-readiness basics') and enumerates exactly what is inspected: robots.txt, sitemap.xml, llms.txt, .well-known/security.txt, homepage JSON-LD. The sibling tools are unrelated audit/utility tools, so no disambiguation is needed and none is missing.

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?

The scope ('AI/agent-readiness basics') and the 'free' qualifier make the appropriate context clear, and the 5-check list implies this is a shallow baseline check rather than a deep audit. It does not state any exclusions or point to a deeper alternative, which keeps it just short of a 5.

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