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

Annotations already cover the read-only, idempotent, non-destructive nature of the tool. The description adds valuable behavioral nuance: token count is approximate (~4 characters per token), extraction uses strict patterns, and EVM addresses are checksum-validated. This sets accurate expectations beyond what annotations provide.

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 dense but every clause adds an output category or an important caveat. Caveats are placed at the end, keeping the main capability list front-loaded. The trailing 'Price: free' is slightly tangential but not harmful.

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 produces many distinct output categories and has no output schema, yet the description does not explain the result shape or how the `extract` boolean alters the response. It is sufficient for selecting the tool, but leaves an agent without a clear expectation of the return structure.

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 0%, so the description needed to explain both parameters. The `text` parameter is implied clearly by the prose, but the `extract` boolean is not mentioned at all; an agent cannot determine what setting it to false does or whether extraction is optional.

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 concrete verbs and resources: 'Count characters, words, sentences, lines and paragraphs', 'estimate LLM tokens', and 'pull out every URL, email, @handle, #tag, number and crypto address'. It is clear about the tool's function, but it does not explicitly differentiate from sibling tools such as text_diff or markdown_convert.

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, no named sibling tools, and no exclusion criteria. The phrase 'Price: free' is cost information, not usage guidance. An agent must infer appropriate usage from the feature list alone.

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