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

With no annotations, the description must carry the behavioral burden. It does disclose that the query is discarded, which is useful privacy-relevant behavior. However, it does not state the return format, possible side effects, error behavior, or how the many other schema parameters are handled beyond their own schema descriptions.

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 short sentences with no filler. The primary action is front-loaded, and the second sentence adds meaningful behavioral information without redundancy.

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?

For a simple length-checking tool, the description plus schema is mostly sufficient: an agent can infer that `query` is the search text. However, all nine parameters are optional, and neither the description nor the schema clarifies what happens when no query is provided or what the exact return value looks like, especially with no output schema present.

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 does not explicitly name the `query` parameter, but the schema's `query` description closely matches the tool intent. The description adds no extra guidance about which of the nine optional fields to populate or that most are irrelevant to this tool.

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 verb ('Count'), the resource ('characters in a search query'), and that the query is discarded. This differentiates it from sibling tools like domain-shape or normalize-url by naming a specific counting operation, though it does not explicitly contrast with a sibling.

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?

No usage context or alternatives are mentioned. The phrase 'search query' implies when the tool might be used, but there is no guidance about when not to use it, what prerequisites exist, or how it relates to other similar count/shape tools.

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