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

Goes far beyond the readOnly/idempotent/openWorld annotations: it discloses latency (~1 minute for a fresh check), 24-hour caching, concrete quotas (5/IP/day, 200/hour, 1000/day global, 300/day per assistant platform, with restoration messaging), the identifying user-agent string, a terms-of-use link, and the explicitly limited methodology for the security and e-mail areas. This is unusually rich behavioral context.

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?

Purpose and result contents are front-loaded, and nearly every sentence carries distinct information (limits, refusals, quotas, disclaimers), so little is wasted. However, it is delivered as one dense run-on paragraph with minimal structural separation, which makes it harder to scan than a bulleted form would be.

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?

There is no output schema, but the description fully specifies the return shape (score, band, six named areas, per-area verdicts, counts, timestamp, source line). Combined with the quota, caching and refusal behavior, an agent has everything needed to call it and interpret results.

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 both parameters (url, lang) are already documented in the schema, including the de/en enum and default. The description adds no parameter-level syntax or format guidance, so the baseline of 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 ('Checks one public website') and enumerates exactly what the result contains: overall score with band, six area scores, per-area verdicts, counts of met/partly met/open/not-checkable, verdict, address, time, source line. No sibling tools exist, so no differentiation is needed and the purpose is unambiguous.

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?

Explicit when-to-use trigger: 'Use it when a user asks how a specific public website performs for visitors, search engines and enquiries.' It also states scope limits (only public http/https on standard ports; IP addresses, internal hosts and opted-out sites are refused with a reason) and clarifies it gives no advice and is not a security audit.

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