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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely new context the annotations cannot convey: sign-in is required and cash on delivery is not returned, which prevents a wasted call and an incorrect offer to the user. It stops short of saying whether the list varies by region or account.

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?

A single dense sentence sequence with zero filler: capability and provider examples first, then the cash-on-delivery exclusion, then the auth prerequisite, then the intended use. Every clause earns its 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?

An output schema exists, so return values need not be explained. For a read-only, no-param lookup, the description covers purpose, exclusions, auth requirement, and the workflow role — nothing an agent needs to call it correctly is missing.

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 nothing for the description to disambiguate; the baseline for a no-param tool applies. The mention of payment_type_id clarifies the output field the agent will consume rather than any input.

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?

Specific verb (List) plus precise resource (available DIGITAL payment methods for checkout) with concrete examples enumerating the providers. It explicitly excludes cash on delivery, so an agent can distinguish this from order-placement siblings without opening a schema.

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?

States an explicit use case: mapping a user-named payment method to its payment_type_id, which is exactly the downstream need before place_order. No alternatives are named, but no sibling offers a competing capability, so the routing risk is low.

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