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

The description discloses that the query is discarded, which is a useful behavioral note about data retention. However, no annotations are provided, so the description carries the full burden of behavioral disclosure. It does not state that the operation is read-only, what the return value looks like, or any error conditions. More detail is needed.

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 and front-loaded, which is good for conciseness. However, it is under-specified for a tool with 9 parameters and no annotations. A few more sentences clarifying the primary parameter and output would make it appropriately sized for the 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 9 parameters, no required ones, no output schema, and no annotations. The description only mentions counting characters and discarding the query. It does not specify which parameter to use, the format of the result (e.g., an integer), or any limitations. The agent lacks critical information to invoke it correctly.

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?

Schema description coverage is 100%, so each parameter has a description. The tool description does not add meaning beyond the schema; it does not identify which parameter is the focus (the 'query' parameter). The schema itself clarifies 'query' as 'Search text; discarded after the length check,' so the meaning is present but the description offers no additional guidance. Baseline 3 applies.

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 and resource: 'Count characters in a search query.' This clearly identifies the tool's function. However, it does not explicitly name the 'query' parameter among the nine schema parameters, and it lacks differentiation from sibling tools beyond the name. Still, the purpose is unambiguous.

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. There is no mention of context, prerequisites, or exclusions. The agent must infer usage from the name alone, which is insufficient for a tool with many parameters.

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