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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose that the query is discarded after the length check, which is a meaningful side-effect note. However, it does not mention the return format (e.g., an integer), error behavior for missing or non-string inputs, or any other edge-case handling. For a simple tool this is minimal but not misleading, so a middle score is appropriate.

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 exceptionally concise: two short sentences that state the purpose and a key behavioral note. Every word earns its place, with no fluff or repetition. It is appropriately front-loaded with the action and resource.

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?

Despite having nine optional parameters, the description only addresses the 'query' parameter. It does not explain whether the other parameters are accepted and ignored, or if they serve any purpose in this tool. There is no output schema, so the return value is undefined. For a tool with this parameter count, the description is insufficient to give an agent full confidence in invoking it correctly, especially regarding parameter interaction and return format.

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 description coverage is 100%, so the baseline is 3. The description adds no extra meaning beyond what the schema already provides for the 'query' parameter (which says 'Search text; discarded after the length check'). It does not clarify the role of the other eight parameters, leaving their semantics entirely to the schema, which already describes them individually. No additional value is added.

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 the action ('Count characters in a search query') and the resource (a search query). It is specific enough to understand the primary function, but it does not explicitly distinguish itself from sibling counting tools like 'hn-front-count' or 'memory-key-count', which are context-specific. The name itself is self-explanatory, but the description could have mentioned its scope relative to those.

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. The description does not mention any conditions, exclusions, or examples of appropriate use. An agent is left to infer from the name alone, which is insufficient for deciding between this and other counting tools.

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