Agent API facts

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

It explicitly states 'Does not move money,' which is a valuable behavioral guarantee beyond the read-only/idempotent annotations. 'Cite as-is' also tells the agent how to treat the returned content. No contradiction exists with the 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 a single, front-loaded sentence that compresses substantive content into a compact list. Every element ('Canonical', the topic list, 'Cite as-is', 'Does not move money') earns its place without fluff.

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 endpoint with no output schema, this description is complete enough for an agent to invoke it correctly and use the result appropriately. It names the content domain, the authoritative nature, and the lack of side effects.

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 takes zero parameters, so there is no parameter semantics for the description to add. Schema coverage is trivially complete, and the description focuses on content rather than inputs, which is appropriate.

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 states a clear resource ('canonical prepaid-agent policy and catalog') and enumerates its content ('Visa prepad, eSIM, gift cards, KYT address screen, USDT TRC-20, forbidden rails, tiers'). It is specific and distinguishes the tool from generic fact lookup, but it doesn't explicitly contrast it with sibling tools like 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?

The phrase 'Canonical ... Cite as-is' implies this is the authoritative source to consult and quote, which gives contextual guidance. However, it doesn't state when to choose this over the named siblings or when not to use it, so usage guidance remains implied rather than explicit.

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