Count text

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

With no annotations, the description carries the full burden. It discloses a key behavioral nuance: reports visible characters separately from code points, which differ for accents and emoji. It also guarantees exact counting. This adds meaningful context beyond the title, though it does not cover edge cases like empty input.

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 sentences with zero filler. It front-loads the core function ('Count characters, words, lines, sentences and bytes') and then adds usage guidance and a behavioral nuance, all in a compact structure.

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?

For a simple one-parameter tool with no output schema, the description covers the main operational aspects: what is counted, precision, and the visible-character/codepoint distinction. It does not explicitly state the return format or handle edge cases, but the described behavior is sufficient for an agent to invoke it correctly.

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?

The input schema already describes the 'text' parameter with 100% coverage, so the baseline is 3. The description does not add further parameter-specific detail, such as encoding or size limits, so it neither enhances nor detracts from 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 explicitly states the tool counts characters, words, lines, sentences, and bytes, with a specific verb and resource. It also emphasizes exactness and distinguishes from token-based reading, making the purpose unambiguous even without naming siblings.

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?

The description provides clear guidance on when to use the tool: 'whenever the answer needs to be a precise number.' It also explains why ('reading tokens is not the same as counting characters'). It does not explicitly list alternative tools or exclusion conditions, so it stops short of full when/when-not coverage.

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