List accessible customers

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

The annotations already indicate readOnlyHint=true and destructiveHint=false. The description adds behavioral detail by explaining the scope of the listing (direct accounts plus client tree), which is not fully covered by the annotations alone. It does not describe the exact output format, but that is not required for a read-only listing tool.

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 concise, consisting of two clear sentences with no redundant information. It front-loads the primary action (list accounts) and provides essential context (reachable with credentials) and a direct use case (find customer_id).

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 has no input parameters and no output schema, the description provides sufficient context: it explains what is listed (accessible accounts), the scope (direct and client tree), and the intended use (finding a customer_id). This is complete for a simple listing tool.

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?

There are no parameters in the schema, so parameter semantics are trivially complete. The description does not need to add parameter-specific information, and the baseline of 3 is appropriate given the high schema coverage (100% with zero 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 clearly states the tool lists Google Ads accounts reachable with the configured credentials, specifying both direct access and the client tree under a login customer ID. This distinguishes it from sibling tools that list other resources like campaigns or ad groups.

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 instructs to use this tool to find a customer_id, providing a clear call-to-action. It implicitly indicates this is the tool for identifying accessible accounts, making the use case unambiguous.

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