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

With no annotations, the description carries the full disclosure burden. 'Query discarded' usefully communicates that the input is not stored, which is good for a seemingly harmless utility. However, it does not state the return type, how empty or missing input is handled, or that all non-query parameters are ignored.

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?

Two short sentences with no filler: the purpose is front-loaded and the side-effect note earns its place. Every word adds information.

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 nine optional parameters, no output schema, no annotations, and a large sibling list, the description is too thin. An agent needs to know that `query` is the only relevant input, that other fields are ignored, and what kind of result is returned; none of that is explicitly stated.

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 `query` property is described as 'Search text; discarded after the length count', which aligns well with the tool description. The description adds no additional parameter-level meaning, and the unrelated sibling-style parameters create confusion but are not contradicted.

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 names a concrete operation ('Count characters') and a target ('a search query'), and 'Query discarded' clarifies that the input is not persisted. It is distinguishable from normalization and validation siblings, but it does not explicitly tie the action to the `query` parameter, and the schema's many unrelated optional fields muddy the mapping.

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 on when to use this tool versus alternatives such as `validate-json`, `normalize-url`, or `memory-key-count`. No contrast, exclusions, or note that only the `query` property is relevant is provided; the only signal is the tool name itself.

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