Add Payment Method

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

The description discloses the key behavioral trait that the operation is unsupported by the API, which goes beyond the annotations (all false). This tells the agent the tool is effectively a stub and should not be invoked, preventing failed calls.

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 two sentences with no filler. The primary action is front-loaded, and the crucial unsupported-operation warning follows immediately.

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?

Given the tool is not exposed by the API, the description provides the essential context: the operation is unavailable and the user should use the Uber app. No output schema is needed, and the description fully prepares an agent to handle a request for this operation.

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 description adds no parameter-specific meaning beyond the input schema. With schema description coverage at 33% (only token has a description), the description should compensate for undocumented parameters like type and label, but it does not.

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 states the action 'Add a payment method' with a specific resource. It also distinguishes this tool from sibling payment management tools by noting the API does not expose the operation, so the purpose is unambiguous.

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 explicitly says when not to use the tool ('The Uber Rider API does not expose this operation') and provides the alternative ('use the Uber app to manage payment methods'). This gives an agent clear guidance to avoid calling this tool.

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