list_accessible_customers

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

With no annotations, the description carries the full burden for behavioral disclosure. It adds value by detailing the exact output format ('customers/1234567890') and clarifies that the digits represent the customer ID, which is not specified in the schema. It does not discuss pagination, ordering, or side effects, but for a simple read-only listing operation this level of transparency is sufficient.

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, front-loaded with the action verb, and every word earns its place. It defines the output format in the second sentence without redundancy, making it highly efficient and well-structured.

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 simplicity of the tool (no parameters, no output schema, no annotations), the description adequately covers the key context: what is listed, the format, and the scope of the login's accessibility. It stops short of specifying the overall return container (e.g., JSON array) but that is easily inferred from 'List the resource names'. For a tool of this complexity, the description is nearly complete.

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, so the baseline is 4. The description does not need to add parameter information, and the empty schema already communicates that no arguments are required. The description's focus on output semantics is appropriate.

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 states the verb 'List' and the specific resource 'Google Ads customers this login can access', with an explicit example of the output format. This distinguishes it from sibling tools like list_campaigns or list_ad_groups which operate on different entities. The purpose is unambiguous and immediately actionable.

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 implies a use case: obtaining customer resource names for a login to use with other tools that require a customer ID. However, it does not explicitly state when to use this tool versus alternatives or provide any exclusions. The guideline is present only implicitly through the phrase 'this login can access', so it's adequate but not explicit.

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