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

No annotations are provided, so the description carries the full transparency burden. It does disclose that the query is discarded, which is a meaningful side-effect statement. However, it does not mention the return format, possible errors, or whether the unrelated optional parameters are ignored, leaving some behavioral gaps.

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 a single concise sentence with no fluff, repetition, or unnecessary detail. It directly communicates the tool's function and a relevant behavioral note in a compact form.

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?

There is no output schema, and the description does not explicitly state the return value (e.g., an integer character count). It also does not address behavior when 'query' is omitted, even though all parameters are optional, nor does it clarify the role of the eight unrelated optional parameters. The core idea is present, but these gaps reduce completeness.

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. The 'query' parameter is clearly described as search text and is consistent with the tool purpose. However, the other eight optional parameters are unrelated to the stated purpose, and the description does not explain why they exist or whether they are ignored, which creates ambiguity despite individual field descriptions.

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's purpose with a specific action ('Count characters') and resource ('search query'), and explicitly notes that the query is discarded. The tool name reinforces this. It is immediately understandable what the tool does.

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 description is self-explanatory for the core use case, but it does not explicitly indicate when to use this tool versus any alternative, nor does it mention edge cases or conditions. There are no sibling tools with similar names, but no direct usage guidance is provided either.

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