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

With no annotations, the description carries the behavioral burden, and 'Query discarded' is a useful disclosure that the query input is not retained. The operation is clearly read-only and non-mutating, though it could still state the return value more explicitly.

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 two short sentences with no filler. The main action is front-loaded and the side-effect note is compact, so every word earns its place.

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 appears simple, but the schema exposes nine optional string parameters while the description mentions only one, and there is no output schema to clarify the return format. An agent is left to infer that only `query` matters and what exact result the tool produces.

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 schema already documents every parameter and many 'discarded' behaviors. The description adds little beyond identifying the query as the operand and does not clarify that the other eight parameters are irrelevant to this tool's function.

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') on a specific resource ('a search query'), so the core purpose is recognizable. It is not a 5 because it does not explicitly differentiate from the many sibling count/check tools, and 'Query discarded' introduces slight ambiguity about what is returned.

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?

The intended use is reasonably implied: call it when you need the character count of a search query. However, the description gives no explicit when-to-use guidance, exclusions, or alternatives, leaving routing among 28 siblings mostly to inference.

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