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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is known. The description adds behavioral context about Unicode-awareness for non-Latin scripts and the 240 wpm reading-time assumption, which are not captured in the annotations or schema.

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 concise sentences: one states the function, one adds a key behavioral note. The third about reading time is also brief and necessary. No filler or repetition of schema annotations.

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 with full parameter documentation, a complete output schema expected, and annotations covering safety. The description covers the main function, Unicode handling, and reading-time assumption. Nothing important is missing for an agent to invoke this tool 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?

Schema coverage is 100% with a detailed description of the 'text' parameter including the 60,000-character cap and client-side split guidance. The tool description adds no additional parameter semantics beyond the schema, so the baseline of 3 applies.

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 verb 'count' and enumerates the seven kinds of counts (words, characters, sentences, paragraphs, reading time) for a block of text. This distinguishes it from sibling tools like character-counter and vowel-counter, which likely target individual metrics.

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 clearly implies usage: whenever the agent needs any of the listed text metrics. It does not explicitly name alternative tools or exclusions, but the breadth of counted metrics provides adequate context for selecting this tool over more specialized siblings.

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