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

With no annotations, the description carries the burden of disclosing side effects, and it does state that the query is discarded. This is a useful transparency signal. However, it does not mention the fate or role of the other eight accepted parameters, nor clarify whether any other processing occurs, leaving the behavioral picture incomplete.

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?

Two short sentences with the action front-loaded and no filler. 'Query discarded' earns its place because it conveys an important behavioral fact that is not otherwise obvious.

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 core operation and data handling are described, but the tool has nine optional parameters, no required parameters, and no output schema. The description does not state that only 'query' is relevant, what the return value looks like, or how to handle the other accepted fields. It is minimally adequate but leaves functional gaps.

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 description adds no parameter-level detail; the schema's 'query' parameter description ('Search text; discarded after the length check') is what actually clarifies the relevant input.

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 specific action ('Count characters') and resource ('search query'), which clearly distinguishes it from the URL/domain/JSON checkers among siblings. It does not explicitly name sibling tools, but the subject is unambiguous. 'Query discarded' adds behavioral context without obscuring 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?

The purpose implies when to use this tool: when the length of a search query is needed. However, there is no explicit guidance about alternatives, exclusions, or when not to use it, so the agent must infer usage from the name and the query parameter description.

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