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

Annotations already declare this is a non-read-only, open-world, idempotent, non-destructive operation, and the description adds important behavior beyond that: creation is always paused, names must be unique in the campaign, the CPC bid acts as a keyword default, and dryRun previews changes. These details materially help an agent understand side effects and constraints.

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 short, front-loaded with the core action, and every sentence carries actionable information about creation state, bidding, naming, language, or dryRun.

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?

For a mutation tool with full schema coverage and safety annotations, the description covers the key behavioral constraints needed to invoke it correctly. The main minor gap is that it does not describe what the tool returns, such as the new ad group id, and there is no output schema.

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%, so the baseline is 3. The description still adds meaning beyond the schema by explaining that cpcBid is inherited by keywords without their own bid and that language is only required when the campaign has no language set.

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 a specific verb and resource: create an ad group in a campaign. It is clear what the tool does, but it does not distinguish itself from sibling tools such as create_ad_group or update_ad_group.

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?

It gives useful operational context: the ad group is always created paused, language is only needed if the campaign has none set, and dryRun can be used to review. However, it does not explicitly say when to choose this tool over the similarly named create_ad_group sibling.

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