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

The description discloses that the query is discarded, which is a behavioral note, but this information already appears in the schema for the query parameter ('discarded after the length check'). It does not describe behavior for the other parameters, nor does it state whether the operation is read-only or has side effects. With no annotations, the description should carry more of the behavioral burden but fails to do so comprehensively.

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 very brief (two sentences) and front-loads the core purpose. However, for a tool with nine parameters and no annotations, it is under-specified, omitting essential information about the other inputs. It is concise but not appropriately sized for the tool's complexity.

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 nine optional parameters, no annotations, and no output schema. The description addresses only one parameter (query) and does not explain the purpose of the other eight, nor the expected return value (though 'count' implies a number). This is severely incomplete for an agent to correctly invoke the tool, making it nearly unusable without additional context.

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 schema provides descriptions for all nine parameters (100% coverage), so the description need not repeat them. However, the description only mentions 'search query', which could mislead an agent into thinking only the query parameter matters, while the schema has many other fields. This adds confusion rather than clarity, so the description provides negative value despite high schema coverage.

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 clear action (count characters) and resource (a search query), which is specific. However, it does not clarify the role of the other eight parameters in the schema, making the tool's full purpose ambiguous. It also does not distinguish it from sibling counting tools like memory-key-count or hn-front-count.

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 guidance is given on when to use this tool versus alternatives. The description simply states the operation, leaving the agent to infer usage context. There are no exclusions or references to sibling tools, so the agent gets no help in tool selection.

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