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

With no annotations, the description carries the full behavioral disclosure burden. It communicates that the tool returns live capability data and implies a read-only operation via 'Returns,' but it does not explicitly disclose whether there are any side effects, authentication requirements, or response characteristics beyond the returned data types.

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 no redundant wording. The first sentence front-loads the core return value, and the second adds a practical usage hint. Both sentences earn their place.

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 no-parameter, read-only capability query, the description covers the essential information: what to expect in the response and when to use it. The lack of an output schema is partially mitigated by the explicit list of returned item types, though a note about response structure would make it fully complete.

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 is trivially complete with 100% coverage. Per the rubric, a zero-parameter tool gets a baseline of 4; the description appropriately focuses on return values rather than parameters.

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 explicitly states the operation ('Returns') and the precise resource: the payment networks, schemes, assets, and facilitator addresses currently supported by PayAI. It is specific enough to distinguish this from sibling tools like settle_payment and verify_payment, which are action-oriented, and even from list_discovery_resources, which implies a different kind of resource.

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 a clear usage context: 'Use it before constructing payment requirements when you need live capability data.' This tells the agent when to invoke it, though it does not explicitly state when not to use it or name alternative tools for exclusion.

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