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

Annotations already cover the safety profile (readOnly/openWorld/non-destructive), yet the description adds genuinely new context: the tool is free, it is rate-limited per IP (and therefore may fail under repeated calls), and its return surface is an inspection of the site's own published metadata. These are traits the annotations do not supply.

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?

Three short pieces — the cost, one dense content sentence with a colon-led enumeration, and the rate-limit caveat — with zero filler. The most decision-relevant facts (free, rate-limited) sit at the edges where they are easy to scan.

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 two-param, no-output-schema read tool, the description covers cost, limits, and the shape of what comes back, which is exactly what is needed given no output schema exists. It stops just short of saying what happens for sites with no llms.txt or sitemap, which would have closed the last gap.

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%, so both parameters are already documented — baseline 3 applies. The description does add a small amount of meaning by implying the robots.txt crawler check is scoped to the caller's own bot, which connects loosely to the user_agent param, but it never explicitly maps that param to that behaviour.

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 enumerates concretely what the card contains (llms.txt/llms-full.txt, sitemap with page count, feeds, language versions, Content Signals, robots.txt crawler allowances), so the resource is unambiguous even though the tool name 'site' is generic. It does not, however, differentiate itself from siblings like preflight or extract, which an agent could plausibly confuse it with.

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?

"Everything an agent should know about a website before using it" implies a reconnaissance/pre-flight use case and the timing (before acting on the site). But it never states when NOT to use it, nor names an alternative sibling (e.g. preflight, extract) for cases where a full site card is overkill.

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