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

The description does disclose that the query is discarded, which is a useful side-effect note. But it does not explain what happens to the many other accepted parameters, whether any external effects occur, or whether only the 'query' field is used. With no annotations, this leaves important behavior undisclosed.

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 very short and to the point, with no wasted words. The two sentences each carry meaning: the first states the action, the second states a behavioral guarantee. It could be more informative, but it is well-structured for its length.

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?

Given the surprisingly complex schema with nine unrelated optional parameters, the description is incomplete. It does not specify the return format (e.g., an integer count), does not clarify that only 'query' is relevant, and does not explain why other parameters exist. This makes the tool hard to use correctly despite its simple stated purpose.

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?

Although the schema has 100% description coverage, most parameter descriptions are irrelevant or confusing for a search-query length tool (e.g., 'Git ref name', 'HTTPS URL to normalize or cite'). The 'query' parameter is described as 'Search text; discarded after the length check', which helps, but the other parameters are not marked as ignored, making the actual input contract unclear.

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 statement 'Count characters in a search query' gives a specific verb and resource, clearly indicating the core function. However, the input schema includes many unrelated properties (ref, url, city, etc.), and the description does not explicitly identify the 'query' parameter as the sole relevant input, so the purpose is slightly muddied.

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 guidance about when to use this tool versus alternatives, no mention of suitable input types, and no exclusions. The sentence 'Query discarded' is about side effects, not usage context.

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