Agent API facts

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds useful behavioral context beyond this: 'Cite as-is' instructs exact quoting, and 'Does not move money' reinforces the no-side-effect nature of the tool in plain language.

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 compact and every phrase carries weight: the scope comes first, followed by a concrete topic list, then two short usage directives. No filler or redundancy.

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 zero-parameter, read-only facts tool without an output schema, the description is largely sufficient: it names the domain, lists covered topics, and gives quoting guidance. It could be slightly stronger by distinguishing itself from overlapping siblings like get_tier_policy, but nothing essential is missing for invoking 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?

The tool has zero parameters and the schema coverage is 100%, so there is nothing to document. The description instead clarifies the content scope of the returned facts, which is the only semantic information an agent needs.

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 identifies the tool as a canonical prepaid-agent policy and catalog reference and enumerates the exact fact domains it covers (Visa prepaid, eSIM, gift cards, KYT, USDT TRC-20, rails, tiers). This is specific and informative, though it does not explicitly differentiate from siblings such as get_tier_policy or get_catalog_placement.

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?

'Canonical... policy and catalog' provides clear context that this is the authoritative reference source, and 'Cite as-is' tells the agent to quote content verbatim. It also excludes transactional use with 'Does not move money.' However, it does not explicitly name alternatives or state when a sibling would be preferred.

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