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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so safety is covered. The description still adds non-obvious behavior: plan-gated date filtering, the per-call quota, and the underlying GET endpoint — useful operational context beyond the 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?

Compact and front-loaded: the resource and the returned dimensions come first, then the plan/quota constraints, then the endpoint. The long enumeration of dimensions is dense but each item conveys an actual returned field, so little is wasted.

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?

With no output schema, the description carries the return-value burden and does so by listing the stat categories returned (sources, referrers, countries, devices, OS, browsers, brands, languages). It does not describe the response envelope or error cases, which is the main remaining 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 description coverage is 100%, so all three parameters (link, date_from, date_to) are already documented, including the exact date pattern and the Team-plan restriction. The description's mention of the date-range plan requirement duplicates the schema rather than extending it, landing at the baseline 3.

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+resource ('Click statistics of one short link') and enumerates exactly which breakdowns are returned, so the agent knows the shape of the result before calling. It is clearly distinguishable from the five sibling tools, all of which are mutating link operations.

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?

Adds real selection context: the date-range filter requires the Team plan or higher, and one call counts against a Free-plan limit of 3 per 60 seconds. It does not explicitly name an alternative tool, but since it is the only read/stats operation among its siblings, the routing is unambiguous.

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