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

The description provides crucial behavioral context beyond annotations: explains the two pipeline paths (SEC EDGAR fast path vs. grounded pipeline), defines all six verdicts, and especially clarifies that 'could_not_verify' means the check did not happen and carries an error—warning callers not to treat it as evidence. This is exactly the kind of nuance an agent needs and goes far beyond the readOnly/openWorld/idempotent hints.

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 lengthy but information-dense, front-loaded with trigger phrases and a clear logical structure. Every sentence contributes useful detail (routing, verdicts, caveat, value prop). It could arguably be tightened, but it earns its length.

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 the complexity of this tool—multiple pipeline paths, a nuanced verdict set, and an important caller-facing caveat—the description covers all essential aspects: what it returns, the meaning of each verdict, how it handles unsupported vs. failed checks, and its advantage over sequential calls. No output schema exists, so the description bears full responsibility for return-value transparency, and it meets that need.

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%, with both parameters (claim and tolerance_pct) already having detailed descriptions. The tool description adds context about the overall verification behavior but does not add new parameter-specific meaning beyond the schema. Baseline of 3 is appropriate when the schema carries the semantic load.

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 a specific verb ('validate', 'verify') and resource ('natural-language factual claims') and differentiates itself from sibling tools by detailing the verification workflow, the two-path routing for financial vs. other claims, and the verdict types returned. This is far beyond a generic statement of function.

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?

Explicitly states when to use: 'Use whenever the agent needs to check whether something a user said is factually correct.' It also describes the internal routing for different claim types, which helps select it over alternatives. However, it does not explicitly mention when NOT to use it or name alternatives like deep_research or ask_pipeworx for general Q&A, so it lacks full exclusion guidance.

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