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

Beyond the annotations (readOnlyHint, idempotentHint, etc.), the description discloses crucial behavioral details: the distinction between 'could_not_verify' (check did not happen) and 'unsupported' (no source exists), and explicitly warns that 'could_not_verify' must not be treated as evidence. It also explains the two internally routed paths (structured vs grounded) and the tolerance override behavior, providing transparency well beyond the structured annotations.

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 moderately sized but well-structured. It opens with trigger phrases, then usage guidance, then technical pipeline details, then return-value explanation, then a critical caller warning, and finally a benefit statement. Each sentence adds value, though some could be tightened (e.g., the example list). It is not overly verbose for the tool's complexity.

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 two execution paths, six verdict types, and an error-state distinction, the description is remarkably complete. It covers the return envelope (verdict, actual value with citation, reasoning), the 'could_not_verify' vs 'unsupported' distinction, and the internal routing logic. The absence of an output schema is compensated by the description's explicit enumeration of possible verdicts and error fields.

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% for both parameters, so the baseline is 3. The description adds meaningful extra semantics for 'tolerance_pct' by explaining its default ('implied by wording, capped at 5') and its use case ('set 1–2 for hallucination detection'). The 'claim' parameter is already well-exemplified in the schema, so the description does not need to add more. Overall, the description enhances parameter understanding 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 clearly states the tool's purpose: natural-language claim verification against authoritative sources. It provides concrete trigger phrases ('fact check', 'verify the claim that…') and specifies the action (returns a verdict and evidence). It also distinguishes itself from sibling tools by noting it 'Replaces 4–6 sequential calls', positioning it as a consolidated verification pipeline.

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 says 'Use whenever the agent needs to check whether something a user said is factually correct' and differentiates between company-financial claims (SEC EDGAR path) and all other claims (grounded pipeline). It does not explicitly state when not to use it, but the clear directive covers primary usage. It also implies this is a replacement for multiple sequential calls, which is useful guidance.

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