list_accessible_customers

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

No annotations are provided, so the description carries full responsibility for behavioral disclosure. It communicates that this is a read-only listing operation and adds a key nuance: it only lists directly accessible customer IDs, implying it does not include accounts accessible via hierarchy. However, it does not disclose return format, pagination, or any other behavioral details beyond the basic action.

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, well-constructed sentence with zero redundancy. It is front-loaded with the verb and resource, and the scoping qualifier 'directly accessible to the configured credentials' is concise and valuable. Every word earns its place.

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 parameters and an output schema exists (as indicated by context signals), the description provides sufficient information for an agent to invoke the tool correctly. The note about 'directly accessible' is important for distinguishing it from hierarchy-aware tools. However, slightly more detail about what this tool returns (e.g., a list of IDs) would have been marginally more complete, though the output schema likely covers that.

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 no parameters, and schema description coverage is effectively 100% (trivially). Per the baseline rule for tools with zero params, a score of 4 is appropriate. The description correctly adds no unnecessary parameter information, since there are none.

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 a specific action ('List') and a specific resource ('Google Ads customer IDs') with a scope ('directly accessible to the configured credentials'). It distinguishes itself from siblings like get_account_hierarchy and list_campaigns by focusing solely on customer IDs rather than campaigns or performance data.

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 does not explicitly mention when to use this tool versus alternatives, nor does it state exclusions. However, the purpose is so specific and distinct from sibling tools that a competent agent can infer when to use it. Still, there is no direct guidance on when not to use it, which would be stronger.

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