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

The description aligns with the readOnly and idempotent annotations, but adds little beyond stating it's a GET request and supports bulk execution. Since annotations already cover safety, there is no contradiction, but the description does not enrich understanding of side effects or edge cases beyond the endpoint.

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?

The description is two sentences long, directly conveys the core function and key parameters, and contains no superfluous text. It is well-structured and easy to parse.

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 simple read-only tool, the description provides sufficient context on purpose and primary parameters. It lacks details on return format or error handling, but given the absence of an output schema and the straightforward nature of the operation, it is reasonably 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 description explains `last` (quantity) and `unit` (day/week/month) but does not clarify `id`, `ids`, or `account`. With schema coverage at 0%, this covers only 40% of parameters, leaving key fields like `account` ambiguous, though `id` is self-explanatory.

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 clearly states it retrieves visit counts for an ad within a time window, with the specific endpoint GET /items/{id}/visits/time_window. This distinguishes it from sibling tools like get_item or list_items, which serve different data needs.

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?

It mentions the required parameters `last` and `unit` and their allowed values, but does not explicitly state when to choose this tool over alternatives or provide context around when it's appropriate to use bulk `ids`. The guidance is implicit rather than explicit.

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