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

With no annotations, the description carries the full burden, and it discloses only that the query is discarded. It does not state what is returned, how empty or missing queries behave, or that the other eight schema parameters appear irrelevant, leaving important behavioral gaps for an agent invoking the tool.

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 front-loaded sentences with no filler. Each sentence adds information: the operation and the disposal behavior.

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?

Despite a 9-parameter optional schema, zero required parameters, no output schema, and no annotations, the description does not specify the return format, the relevant parameter, or behavior for missing input. It is minimally usable but incomplete for reliable invocation.

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%, and the 'query' property is explicitly described as 'Search text; discarded after the length check', so the schema does most of the work. The tool description adds no further mapping and fails to warn that the other eight optional parameters are likely irrelevant, but it does not contradict the schema.

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') on a specific resource ('a search query') and notes the input is discarded, which distinguishes it from the many shape-check and fetch siblings by its counting intent. It is slightly ambiguous which of the nine schema parameters counts as the search query, but the 'query' property description aligns with it.

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 choose this tool over siblings such as memory-key-count, hn-front-count, or validate-json, and no exclusions or prerequisites. The intended use is only implied by the name and one-line description.

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