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

Annotations already cover the safety profile (readOnly, openWorld, non-destructive), and the description adds substantial context beyond them: expected latency (4-9s), the x402 payment requirement, and the no-charge-on-failure guarantee. Those are exactly the traits an agent needs to decide whether to invoke and what to expect on error.

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?

Four dense sentences, front-loaded with purpose and return shape, then guidance, then constraints and failure behavior. Every sentence carries information the agent cannot get from structured fields; nothing is redundant.

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?

There is no output schema, so the description compensates by naming the return object and its verdict enum values (supported, contradicted, unclear). Combined with latency, payment, and failure semantics, an agent has everything needed to call this 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?

Schema coverage is 100%, so the claim parameter's type, length bound, and statement phrasing are already documented, which sets a baseline of 3. The description adds meaning beyond the schema by constraining cardinality ('one claim per call') and providing a concrete example phrasing.

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 ('Checks one factual claim against the live web') and names the exact return shape. It explicitly distinguishes itself from the sibling bob_research, so an agent can route between the two without opening either schema.

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?

Gives explicit when-to-use ('verify a specific statement'), the alternative and its condition ('use bob_research for open questions'), plus operational guidance on one claim per call, plain-statement phrasing, and splitting compound claims. Nothing is left to inference.

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