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

Annotations already declare readOnly/idempotent/non-destructive, and the description layers on genuinely new operational facts: statelessness, a 32 KB payload cap, 60 RPM throttling, demo-mode or L402 payment (20 sats), and an HTTP 400 failure mode for invalid input. A mild tension exists with openWorldHint=false given the outsourced 'authoritative consensus sources' and Lightning payment path, but this reads as a hosted proxy rather than an outright contradiction.

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?

Two sentences with zero filler, front-loading the action and outcome before routing guidance and then operational constraints. Parenthetical packing is dense but every clause (limits, auth, error code) carries information an agent needs.

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?

An output schema exists so return values need not be described, and the description still covers the remaining gaps an agent would hit: size limit, rate limit, statelessness, payment/auth route, and error behavior. Nothing material for correct invocation is missing at this complexity level.

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 baseline is 3; the description adds value by disclosing a default that the schema does not state ('verification_rigor' defaults to 'multi_source_consensus') and by tying the 32 KB cap to the claim input. It does not explain the tradeoffs between the three rigor enum values, which would have earned a 5.

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 ('Audits factual statements against authoritative consensus sources') plus the output it produces ('truthfulness scores with counter-evidence'). It explicitly distances itself from extract_scholarly_citations, but does not differentiate from the similarly named sibling audit_response_factuality, leaving one close overlap unresolved.

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 concrete triggering conditions ('checking disputed claims, detecting AI hallucinations, or validating quotes before citation') and names an alternative with the condition that selects it ('for formatting academic citations, use extract_scholarly_citations'). No guidance is offered on when to prefer it over audit_response_factuality, so it stops short of the 5 level.

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