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

With no annotations, the description carries the full behavioral burden, and it only offers 'Query discarded' as a transparency statement. While this usefully signals a stateless, side-effect-free call for the query parameter, it says nothing about the other 8 parameters, error behavior, or side effects beyond the length check.

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 essential claim is front-loaded and each word carries weight. The description is appropriately compact for the tool's apparent single-purpose nature.

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?

Even though the tool appears simple, it has 9 parameters and no output schema or annotations. The description doesn't cover what the other 8 parameters do, whether they must be ignored, how errors surface, or what the return format looks like. For a tool wrapped with a disjoint schema, this is incomplete.

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 per the rubric the baseline is 3. The description adds only a bit beyond the schema (that the query is discarded), which does not meaningfully clarify what to do with the 8 non-query parameters or why they exist alongside a query-length function. It doesn't compensate for the mismatch between the described purpose and the schema's parameter list.

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 verb and resource: 'Count characters in a search query.' It is clear at the sentence level. It does not explicitly distinguish itself from siblings (e.g., hn-front-count or memory-key-count), and the schema surfaces 9 largely unrelated parameters, so an agent can't tell from the description alone that only the 'query' parameter is involved.

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?

No guidance exists for when to use this tool versus alternatives. It never mentions siblings, conditions for use, or when not to use it. The only clue is the tool name itself, which the description does not reinforce or expand.

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