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

With no annotations available, the description carries the full burden of disclosing behavior. 'Query discarded' does add a useful side-effect note. But the description does not explain whether the other eight schema parameters are ignored, rejected, or relevant, nor does it clarify the exact return value. This unaddressed mismatch between the narrow description and the broad schema is a significant behavioral gap.

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 very short sentences with the action verb front-loaded and no filler. 'Query discarded' earns its place by disclosing a side-effect/privacy property. This is appropriately sized 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?

Despite a simple core operation, the tool exposes nine optional parameters, has no annotations, and has no output schema. The description does not explain the role of the extra parameters, whether they are ignored, or what the return type is. An agent reading only this definition cannot confidently predict the full behavior of a call.

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 the baseline is 3; each parameter already has its own description. The text naming a 'search query' maps clearly to the query parameter, but it adds no new meaning beyond the schema. It also fails to help disambiguate why so many unrelated parameters are present.

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 uses a specific verb ('Count') and object ('characters in a search query'), which clearly matches the tool name and distinguishes it from sibling counters by the search-query focus. It is not a tautology and is understandable. However, it does not explicitly address the large set of unrelated parameters in the schema, which slightly weakens purpose clarity.

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?

The purpose statement implies the usage: call this when you need the character length of a search query. It does not mention alternatives, exclusions, or when not to use it, and it never relates the tool to sibling tools like validate-json or normalize-url. 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.