verify_claim

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

With no annotations at all, the description carries the full burden and does well: it discloses that the tool is paid, that verification runs against the live web, and that results include a three-valued verdict, evidence, and sources checked. It omits latency, rate limits, failure/error behavior, and repeat-call cost implications, which keeps it short of a 5.

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?

Three tight sentences, front-loaded with the core action and cost warning, with output shape following. The closing line ('Grounds an agent's statements in reality') is motivational rather than operational and is the only low-value sentence.

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 two-parameter tool with no output schema and no annotations, the description does the essential work: it names the return fields and the verdict enumeration, and flags the paid nature. Remaining gaps are secondary (rate limits, failure modes, what 'unverifiable' typically means), so it is close to complete but not exhaustive.

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% for both parameters, so the baseline is 3. The description reinforces that url is optional and gives a concrete claim example ('example.com uses Cloudflare') that hints at expected claim phrasing, but adds no format or constraint detail the schema doesn't already supply.

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 and resource ('Check a claim against the live web') and adds a concrete claim example plus the output shape (verdict, evidence, sources), so an agent knows exactly what comes back. It doesn't explicitly name or contrast with siblings like check_domain or is_site_up, so differentiation is inferable rather than stated.

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?

'Grounds an agent's statements in reality' implies the usage context (verify a factual assertion before asserting it) and 'Paid' flags a cost consideration. However, there is no explicit when-not-to-use guidance, no mention of alternatives, and no statement of prerequisites or limits — the agent must infer the boundary from sibling names.

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