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

With no annotations, the description carries the full burden of behavioral disclosure. It does state 'Query discarded,' which informs the agent that the input is not persisted, but it does not describe what the tool returns, how the count is computed, or whether the other eight schema 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?

The description is two short, front-loaded sentences with no wasted words. However, given the unusually broad nine-parameter schema, the brevity borders on under-specification, so it earns a 4 rather than a 5.

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 nine optional parameters and no output schema, yet the description does not clarify which parameter is actually used, what the return value looks like, or whether the other parameters are irrelevant. An agent could reasonably wonder whether to pass ref, city, json, or other fields, making this a significant completeness gap.

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 documents every parameter. The description adds little beyond what the query parameter's own schema description already says ('discarded after the length check'), so the baseline of 3 is appropriate.

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 operation ('count characters') and a specific target ('a search query'), making the core purpose clear. It does not explicitly differentiate from sibling count tools like memory-key-count or hn-front-count, but the 'search query' scope gives enough distinction for a 4.

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, and no mention of exclusions or prerequisites. The only implied context is that it handles search queries, but sibling tools like memory-key-count and hn-front-count are not addressed.

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