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

With no annotations, the description must carry behavioral disclosure. It states 'Query discarded,' which is a useful trait, but it does not disclose what happens to the other parameters, whether any network access occurs, or what the output format is. The schema mentions 'discarded after the shape check' for some fields, but that is not in the description, leaving the tool's full behavior opaque.

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 extremely concise (two short sentences) and front-loads the primary action. However, its brevity omits critical context about the other parameters, so while it is concise, it is not optimally informative.

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 tool with 9 parameters and no output schema, the description is severely incomplete. It does not explain the purpose of the other parameters, the relationship between them, or what the return value is. An agent cannot reliably understand how to call this tool correctly based solely on the description.

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 description coverage is 100%, so each parameter is documented in the schema. The description adds no extra semantic meaning beyond restating that the query is discarded, which is already in the schema. The baseline of 3 is appropriate because the schema carries the semantic burden.

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 in a search query') and a clear resource, but the input schema contains 9 diverse parameters (ref, url, city, feed, etc.) that the description does not address, making the tool's actual scope ambiguous. It does not differentiate this tool from sibling shape-check tools like domain-shape or validate-json.

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. There is no mention of conditions, exclusions, or alternative tools. The agent is left to infer usage from the name and schema.

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