list_ad_units

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

With no annotations, the description carries the full burden. It states a list operation (implying read-only) but does not explicitly mention that it is safe, nor does it disclose any side effects, permissions, or output details. The provided account_name format is helpful but pertains to parameter semantics rather than behavior.

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 sentence that is front-loaded with the core action and includes the critical parameter format. There is no wasted wording, and it is appropriately concise for a simple tool.

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?

The tool is simple (one parameter) and has an output schema, so the description need not cover return values. However, it omits any mention of pagination, filtering, or read-only semantics. It is minimally adequate but could benefit from a note about the nature of the list (e.g., that it is read-only).

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 schema has zero description coverage for the single parameter, so the description must compensate. It provides the exact expected format of account_name ('accounts/pub-1234567890123456'), which is essential for correct invocation. This goes beyond the schema's bare type definition.

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 ad units under an account, with a specific verb and resource. It doesn't explicitly distinguish from sibling tools, but the resource (ad units) is distinct from accounts, apps, and reports, so it is understandable.

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?

No guidance is provided on when to use this tool versus alternatives. It does not mention prerequisites, such as needing an existing account, nor does it contrast with other list/generate tools. The usage context is left entirely to inference.

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