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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds value by disclosing the cost (Paid resource; x402 price is $0.002 USD per call) and clarifying that it evaluates facts against rules (implying no side effects). This goes beyond annotations without contradicting them.

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 three sentences, each earning its place: the first states the core function, the second scopes usage and exclusions, and the third gives cost. It is front-loaded with the primary action and contains no redundant phrasing.

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?

The tool has nested objects and two required parameters, but the description does not explain what facts should look like or what constitutes a valid rule beyond the schema. It mentions 'returns blocking violations and warnings' but does not describe the return format or any error behavior. With no output schema and low parameter guidance, the description leaves important gaps for an agent to call it 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 description coverage is 0% – the description does not explain the 'facts' object or the structure of 'rules' beyond what the schema already provides. It uses generic terms like 'caller-supplied facts' and 'caller-supplied rules' but offers no guidance on how to construct valid inputs. Since coverage is 0%, the description must compensate but fails to do so.

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 verb and resource: 'Evaluates caller-supplied facts against explicit caller-supplied rules and returns blocking violations and warnings.' It specifies the domain (trust identity permission / execution risk) and distinguishes itself from legal, identity, sanctions, fraud, contractual, or regulatory adjudication. This makes the tool's purpose unambiguous and separates it from sibling policy engines.

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 provides explicit domain boundaries: 'Intended for trust identity permission / execution risk. Do not use for legal, identity, sanctions, fraud, contractual, or regulatory adjudication.' This gives clear when-to-use and when-not-to-use guidance, though it does not name specific alternative tools. It also mentions it is a paid resource, which informs cost-conscious selection.

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