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

With no annotations, the description carries the full burden; it discloses the scope ('accounts the connected Google account can open') and the read-only implication of 'List', plus the MCC distinction. It does not mention auth requirements, whether accounts are paginated, or what happens when the connected account has no access.

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?

Two dense sentences, front-loaded with what is returned, followed by the downstream chaining instruction. No filler.

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?

With no output schema, the description usefully enumerates returned fields and explains how ids feed ads_report, making it callable without further context. Minor gap: no pagination or multi-account behavior for the `account` parameter.

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?

Schema description coverage is 100% for the single `account` parameter, so the baseline is 3. The description only obliquely references the connected-account concept and adds no format or override semantics beyond what the schema already says.

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?

States a specific verb (List) and resource (Google Ads accounts) and enumerates the returned fields: customer id, name, currency, and MCC flag. It is clearly distinguishable from siblings like ads_report, which consumes the ids this tool produces.

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?

Explicitly instructs the agent to pass the id to ads_report and to use a manager's id as login_customer_id for accounts reached through it, which is real routing guidance. It does not state an explicit when-not-to-use or that this must be called first to discover ids.

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