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

The statement 'Query discarded' discloses a data-handling behavior (no persistence) but this is also already present in the query parameter schema. With no annotations, the description still leaves return format, failure behavior, and treatment of the other fields unspecified.

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 compact and front-loads the main purpose. It loses one point because 'Query discarded' repeats information already in the schema rather than adding new value.

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?

With nine optional parameters and no output schema, the description leaves some ambiguity, but the schema plus the word 'count' give a minimally viable contract. It does not explicitly state that only the query parameter matters or what the exact return type is.

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 description does not need to compensate for missing parameter docs. It adds only the high-level phrase 'search query' while the query parameter description already says 'Search text; discarded after the length check.'

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 specifies a concrete action ('Count characters') and a concrete resource ('a search query'), which clearly sets it apart from sibling count/length tools like memory-key-count and hn-front-count. It is not a tautology because it spells out the unit of measurement.

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, no exclusions, and no note about which of the nine optional parameters is the relevant one. The agent must infer usage from the tool name and the input schema.

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