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

The description mentions that the query is 'discarded', which is a minimal behavioral note. However, it does not explain that other parameters in the schema are ignored or how the tool handles input validation. Without annotations, the description fails to disclose whether any side effects occur beyond discarding the query, leaving significant behavioral ambiguity.

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 that directly communicates the core functionality. It avoids unnecessary detail or repetition, making it easy to parse quickly. The structure is optimal for a simple tool.

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 description omits important contextual details such as the expected return value (e.g., an integer count), error handling, or any constraints on the query length. It also does not explain the relationship between the many schema parameters and the tool's actual purpose, leaving the overall context incomplete. Given the tool's simplicity, a short but more explanatory description would be needed.

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?

While the schema covers 100% of parameters, the description only addresses 'query'. The schema lists many unrelated parameters (e.g., 'ref', 'url', 'zone') with generic descriptions like 'discarded after the check', but the tool description does not clarify which parameters are actually used or how they relate to the counting operation. This mismatch creates confusion and adds no meaningful guidance beyond the schema.

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 function: counting characters in a search query. The verb 'Count' and the object 'characters in a search query' are specific and unambiguous. This distinguishes it from other count-related tools by focusing on search queries.

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 provides no guidance on when to use this tool versus alternatives like 'memory-key-count' or 'hn-front-count'. It lacks any context about typical use cases, prerequisites, or situations where this tool is preferred. The user is left without direction on selecting this tool.

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