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

With no annotations provided, the description carries the full burden and does disclose one meaningful behavioral trait: the query is discarded. However, it does not clarify that the other eight schema fields appear irrelevant to the count, nor does it describe the return value, leaving some behavioral uncertainty.

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 sentences with no filler, and the core behavior is front-loaded. Every word adds useful information.

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 is simple and the schema documents every parameter, so extensive description is not required. Still, with no output schema and no explicit statement that only `query` is used, an agent might wonder whether parameters like `url`, `host`, or `zone` affect the result.

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 a baseline of 3 is appropriate. The description reinforces that `query` is the search text being counted, but it does not help an agent understand how to treat the many other optional parameters that look decoy-like.

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 uses a specific action ('Count characters') and identifies the exact resource ('a search query'), while also noting the query is discarded. This clearly differentiates it from siblings like memory-key-count and hn-front-count, which count different things.

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 about when to use this tool versus alternatives, nor any mention of what makes it distinct from sibling count/shape tools. The agent must infer usage purely from 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.