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

With no annotations, the description carries the behavioral burden; it usefully discloses five free trial calls per signed wallet, indicating a wallet-based access and quota model. It does not explain post-trial terms, counting behavior, or other invocation constraints, although the stated operation suggests non-mutating analysis.

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 short and front-loads the operation, with the trial information placed second. The leading “Word Frequency:” label and emoji add slight redundancy but do not materially hurt scanability.

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 one-parameter tool, the basic call is mostly inferable, but there is no output schema and the description does not explain the returned counts or their ordering. Missing tokenization and case rules, sibling differentiation, and post-trial access terms leave important selection and invocation questions unanswered.

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 schema's sole text property has no description, and the tool description only repeats that the operation is performed “in text.” It adds no guidance on whether the input is required, size or format limits, or how case, punctuation, and whitespace are handled.

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?

“Count word frequency in text” provides a specific operation, resource, and input domain, making the basic purpose clear. It does not distinguish the tool from siblings such as x402-word-count, x402-word-density, or x402-keyword-density.

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 operation implies a general use case, but the description never explains when to choose this tool over related text-analysis tools or when not to use it. The trial note concerns access and quota rather than tool-selection guidance.

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