List Waymo payment methods

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

Annotations already declare readOnlyHint and openWorldHint. The description adds useful context beyond those annotations by clarifying that only safe labels and IDs are returned, not full sensitive payment details, and that the results are scoped to what the booking tool accepts.

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, efficient sentence with no filler. The key qualifier ('safe') and scope ('accepted by the booking tool') are front-loaded, and every word adds meaning.

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 list tool with an output schema and annotations covering safety, the description is complete. It states exactly what is listed, the scope, and the safe nature of the data, leaving no critical gap for an agent to call it.

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 covers everything vacuously. With no parameters to document, the description does not need to add parameter detail; the baseline of 4 applies.

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 uses a specific verb ('List') and a specific resource ('safe payment-method labels and IDs accepted by the booking tool'). It clearly distinguishes this tool from ride-oriented siblings like waymo_ride_history and waymo_book_ride.

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 'accepted by the booking tool' implies this should be used to retrieve usable payment methods before booking, but it does not explicitly state when to use it versus alternatives. No exclusions or alternative routing are mentioned, making the guidance only implicit.

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