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

No annotations exist, so the description carries the full behavioral burden, but it is a simple read-style stats tool and the phrasing ('which came, how many times') signals a non-mutating query. It usefully discloses the categorization scheme (AI crawler / search engine / browser), which is real context. It still omits auth needs, latency, and whether results are aggregated or per-day, so it does not fully compensate for the missing annotations.

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?

A single front-loaded sentence that states the resource, the categories, and the counted quantity with no filler. It is appropriately sized, though it is brief enough that it trades conciseness for the missing parameter detail.

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?

An output schema exists, so return-value shape is covered and need not be explained here. What remains missing is the meaning of the 'days' window and any safety/permission context, which matters because there are no annotations to fall back on. Adequate for a trivial stats endpoint, but not fully complete.

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?

The schema has 0% description coverage for the single 'days' parameter, so the description was expected to compensate and does not. It never cites the parameter, its unit, or its default of 7, leaving only the vague word 'recent' to imply the time window. This is a clear gap for a one-parameter tool.

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 gives a concrete verb and resource: it reports which visitor families (AI crawlers, search engines, browsers) have visited recently and how many times each. That is specific and unambiguous. It gains no credit for sibling differentiation, though the sibling list (post_message, read_messages) is unrelated so no confusion is possible.

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?

There is no explicit guidance on when to call this versus alternatives, nor any stated prerequisites. The word 'recent' implies a time-scoped report but the agent must infer that context on its own. No exclusions or routing hints are offered.

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