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

With no annotations, the description must carry the behavioral burden, and 'Query discarded' is a useful disclosure indicating the input is not retained. However, it does not clarify whether the operation is fully read-only, what happens to the other eight accepted properties, or whether any side effects occur beyond the count.

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 short sentences with no filler and the main action is front-loaded. Every word earns its place, making this an appropriately concise description for a simple counting tool.

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 nine optional parameters, no output schema, and no annotations, the description is too thin for an agent to confidently invoke the tool. It does not specify the return format, whether `query` is effectively required, or whether the other parameters are ignored or cause errors.

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 input schema already documents all nine parameters at 100% coverage, so the description adds little beyond specifying the query focus. The schema carries the semantic weight, and the description does not compensate with additional parameter-level detail.

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 states a clear action and resource: count characters in a search query, which matches the tool name and the `query` parameter. It does not explicitly distinguish itself from sibling tools, but the resource is specific enough to convey the core purpose.

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 on when to use this tool versus alternatives like memory-key-count or validate-json, nor any exclusions or prerequisites. The schema's nine optional fields also make it unclear whether only `query` should be supplied or whether other fields are acceptable.

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