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

With no annotations provided, the description carries the full burden and does disclose the key behavioral trait: it is discover-only and does not spend or mutate the ledger, which is exactly the safety signal an agent needs. It omits pagination/rate-limit details, but for a zero-argument read-only listing that gap is minor.

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 short sentences, front-loaded with the purpose followed by the behavioral guarantee. Every clause earns its place, and the parenthetical field list efficiently previews the response.

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?

There is no output schema, so the description usefully compensates by naming the returned fields. For a parameterless discovery tool with no annotations, the purpose, safety profile, and return shape are all covered with nothing essential 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 per the rubric this hits the baseline of 4. The description correctly implies no filtering input is needed and adds no misleading parameter claims.

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?

States a specific verb (List) and resource (payment providers available for agent checkout), and even enumerates the returned fields (id, enabled, mode, rails). This clearly distinguishes it from the create_checkout and poll_checkout siblings, which are action tools rather than discovery.

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?

"Discover-only; does not spend or mutate ledger" frames the context of use as pre-checkout discovery, which tells an agent when this is appropriate. It stops short of explicitly naming alternatives (e.g., 'call this before create_checkout'), so it is clear context without explicit routing.

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