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

With no annotations provided, the description carries the full burden and discloses the verdict types, confidence score, citations, signed/unsigned tiers, rate-limiting, and payment mechanics. The only slight imprecision is saying the result comes 'as a signed attestation' when the free tier is explicitly described as unsigned, but the following sentence clarifies.

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 tightly written: the core verb and resource appear in the first sentence, and every subsequent sentence adds necessary pricing, transport, or output context. There is no filler or restatement of the tool name.

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 single-parameter tool with no annotations and no output schema, this description covers the key things an agent needs: what inputs to use, what output to expect, whether it is safe/read-only, and when telemetry or payment are required. The only minor caveat is the signed/unsigned confusion, but the detailed caveats make the behavior actionable in all common scenarios.

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 100% and the single 'claim' parameter is already documented as 'A single factual claim, 8-600 characters.' The description reinforces that the input should be a factual claim and connects it to fact-checking behavior, but it does not add substantial parameter-level meaning beyond the schema.

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 names a specific verb ('fact-check'), a specific resource ('a single factual claim'), and the method ('against web evidence'), so an agent can immediately distinguish this from sibling verification tools. The 'claim' scope also differentiates it clearly from verify_business, verify_freshness, and verify_price.

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 says when to use it — 'before your agent relies on it' — and explains the context of being a hallucination guard. It does not explicitly state which sibling to prefer for non-claim verification tasks, but the claim-oriented framing implies the boundary.

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