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

With no annotations, the description carries the transparency burden. It does disclose that the query is discarded rather than stored or returned, which is useful. However, it does not say what the output is beyond a character count, whether the other accepted parameters are ignored, or whether any side effects occur.

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 short, front-loaded, and free of filler. It loses a point because its brevity omits the disambiguation needed for a tool with nine optional parameters.

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 no output schema, no annotations, and nine optional parameters, the description is underspecified. An agent cannot tell which parameter to populate, whether other parameters are acceptable, or what form the returned character count takes. The schema partially compensates, but the definition as a whole is incomplete.

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 the baseline is 3. The description adds no parameter-specific mapping; it never says that the `query` parameter is the one to count or what should be done with the other eight optional parameters. The schema's own `query` description fills the gap, but the oversized parameter set remains ambiguous.

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 action ('Count characters') on a specific resource ('a search query') and adds a behavioral note that the query is discarded. It is enough to distinguish the tool from the sibling shape/validation tools, though it does not explicitly reference the `query` parameter or the other eight schema fields.

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?

There is no guidance about when to use this tool instead of siblings such as memory-key-count or validate-json, nor about when not to use it. The conditions that would select this tool are implied only by the name and terse description.

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