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

With no annotations, the description carries the full burden of behavioral disclosure. It explains the tool's rate-limiting on the free tier, the optional payment for no daily limit, and the signed vs. unsigned attestation behavior. This is more than typical, though it doesn't detail what happens on invalid input or network failures, but the essential behavior is well covered.

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 a single paragraph that is information-dense but not bloated. It front-loads the core purpose and then expands on features and payment options. The length is justified by the complexity of the signing and payment details, and every sentence serves a purpose, though it could be slightly more structured for readability.

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?

Given a single parameter, complete schema coverage, no output schema, and no annotations, the description is thorough. It covers the tool's function, outputs, signing mechanism, rate limits, and payment alternatives. It misses only minor details like error handling or response format specifics, but overall it provides sufficient context for an agent to call 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 schema covers the claim parameter with a character length constraint, but the description adds important context: it clarifies that the claim must be factual and single, and it explains the significance of the claim in the fact-checking process. With 100% schema coverage, a baseline of 3 is expected, but the description elevates it by hinting at the claim's role in the verdict.

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 clearly states the tool's purpose: fact-checking a claim against live web evidence, with specific outputs (verdict, confidence, citations) and a signing mechanism. It distinguishes itself from sibling tools by focusing on general claims rather than business, freshness, or price verification.

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 explicitly explains when to use the tool (before relying on a claim, for misinformation review, as a hallucination guard) and provides guidance on alternatives (free vs. paid tiers, different transport methods). It also mentions alternatives like POST /verify/claim, ensuring the agent knows the options.

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