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

The description adds the behavioral note 'Query discarded,' indicating the input is not retained, and 'Count characters' implies a read-only operation. Since no annotations are present, this disclosure is valuable, though it does not address potential return format or other side effects.

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 highly concise: two short sentences with no fluff. It front-loads the primary action and includes a useful side-effect note. It earns a 4 for efficiency, but the brevity contributes to the ambiguity noted.

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 the schema has seven unrelated string parameters and no output schema, the description is incomplete. It neither indicates which parameter represents the search query nor states the return value (presumably the character count). An agent cannot confidently invoke this tool correctly based on the description alone.

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?

Even though the schema's per-property descriptions are detailed (coverage is high), the tool description fails to map the 'search query' to any of the seven schema properties. This creates confusion about which parameter to pass, and the description adds no clarifying meaning 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 action ('Count characters in a search query') and, by its subject, distinguishes itself from sibling count tools. However, the resource 'search query' does not correspond to any parameter in the input schema, which lists ref, url, city, feed, host, json, and path. This mismatch makes the purpose vague in practice.

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 about when to use this tool versus alternatives. The description does not mention any context, prerequisites, or exclusions, such as which parameter constitutes the search query or when this tool would be preferred over other count/shape-check tools.

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