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

With no annotations, the description carries the full burden. It states 'Query discarded' but does not disclose that other parameters (ref, url, city, etc.) are also accepted and discarded, nor that the tool likely performs shape checks on them. This omission could mislead the agent about the tool's actual behavior.

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 short (two sentences) and front-loaded with the primary action, which is good. However, it omits critical context about the schema's other parameters, making it under-specified rather than appropriately concise.

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?

Given 9 optional parameters, no required fields, no output schema, and no annotations, the description is incomplete. It does not explain the purpose of the additional parameters, what the tool returns, or how it handles multiple inputs. An agent would be uncertain whether to pass only 'query' or also other fields.

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 descriptions cover 100% of parameters, so the schema already documents each field. The tool description adds no meaning beyond the schema, and it fails to clarify why unrelated parameters exist when the stated purpose is only query length. Baseline 3 applies because the schema is sufficient, but the description does not enhance understanding.

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 verb and resource ('Count characters in a search query'), but it is ambiguous given the schema lists 8 other parameters (ref, url, city, etc.) with no explanation of how they relate to the stated purpose. It does not distinguish itself from siblings like 'hn-front-count' or 'think-steps'.

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 provided on when to use this tool versus alternatives. The description does not mention any conditions, exclusions, or related tools, leaving the agent to infer usage from the name alone.

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