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

The description states that the query is discarded after the length check, which implies no persistence side effect and adds some transparency. However, it does not clarify how the other eight input fields are handled or whether any external calls occur, and no annotations are provided to fill this 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 short and to the point with no filler words. It could include more detail, but it is not verbose or redundant.

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?

The tool has a complex schema with nine optional parameters and no output schema, but the description does not tie these together or state the return type (e.g., character count, code points). It also does not explain error behavior or which parameters are ignored, so the operational context is incomplete.

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 'query' parameter is described as search text that is discarded after the length check, which adds useful meaning. But the other eight parameters have descriptions that appear unrelated to a query-length tool (e.g., IANA timezone, JSON validation), creating confusion about whether they are actually used.

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 tool counts characters in a search query, which matches the tool name and indicates a specific action. It does not explicitly name which parameter is the query, but the schema includes a 'query' field that aligns with the 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 sibling count/length tools such as memory-key-count or hn-front-count. The description provides no context about appropriate scenarios or alternatives.

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