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

The description explicitly discloses that the query is discarded, which is a meaningful privacy/behavioral trait given that no annotations are present. It does not describe return behavior or counting rules (e.g., whitespace or encoding), so the burden is only partially met.

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 terse sentences with no filler: the first names the operation and the second states the disposal guarantee. It is front-loaded and skimmable, appropriate for a simple utility.

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 schema has no output schema and no annotations, but the description's 'Count characters' implies the return value and the well-documented parameters mitigate invocation ambiguity. The definition is minimally adequate for a trivial tool, though it leaves the exact output format and the fact that only `query` is relevant unstated.

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 schema already explains every parameter, including `query` ('Search text; discarded after the length check'). The tool description adds no parameter-level meaning, matching the baseline of 3 for high-coverage schemas.

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 concrete operation ('Count characters') on a specific resource ('search query'), so an agent knows what action is performed. It does not, however, name the relevant `query` parameter or distinguish itself from sibling count/length tools, so it is clear but not fully differentiated.

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 description provides no guidance on when to use this tool versus alternatives such as `memory-key-count`, `normalize-url`, or `validate-json`. There are no exclusion conditions or context cues beyond the tool name, so an agent must infer applicability.

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