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

With no annotations, the description carries the full burden, and it does disclose useful traits: the upstream provider is DeepSeek, the response is a JSON claim list with verdicts plus notes, and there is a metered free trial tied to a signed wallet. It does not state auth/payment requirements explicitly, whether the call is billed after the trial, latency, or how long the text may be.

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?

A single front-loaded sentence that gets to the point, but the trailing emoji/promo clause ('🆓 5 free trial calls per signed wallet') is marketing rather than operational guidance and could be stated more cleanly.

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 tool with five undocumented parameters, no annotations and no output schema, the description leaves too much unresolved: no auth/payment requirement detail, no input field disambiguation, and no scope limits on the text to be checked.

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% across five parameters (text, input, label, labels, content), and the description only mentions 'text'. It leaves an agent unable to tell which field actually carries the payload or what label/labels are for, which is a real ambiguity given the near-duplicate input/content pair.

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?

States a specific verb+resource ('Fact Check: sends text to DeepSeek') and names the output shape (JSON list of claims with true/false/unverifiable verdicts and notes). It does not distinguish itself from close siblings such as x402-hallucination-check, x402-verify or x402-textual-entailment, so it stops short of a 5.

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?

No when-to-use guidance at all — nothing says when to pick this over x402-hallucination-check or x402-ai-ask, and nothing explains the trial-vs-paid path beyond a bare quota mention. The '5 free trial calls per signed wallet' line hints at a payment gate but gives no actionable routing instruction.

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