Create ad plan (campaign)

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

Annotations already indicate it is a mutation (readOnlyHint=false) and not destructive. The description adds useful behavioral context: money fields use account currency, and the 'extra' field merges verbatim into the request body. This goes beyond the annotations, though it doesn't describe return behavior or side effects.

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?

Three short sentences, no fluff. The most important info (creates an ad plan) is first. Every sentence adds value: creation action, currency context, and extra field usage.

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's complexity (9 parameters, nested objects, no output schema), the description is adequate but lacks information about what the tool returns (e.g., the created ad plan ID or full object). With openWorldHint=true, some gaps are acceptable, but for a creation tool, return behavior is expected.

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 coverage is 100% with descriptions for all parameters. The description adds meaning by clarifying that money fields are in account currency and that 'extra' is for complex fields. This raises it above the baseline of 3, as it provides practical currency context and usage hints.

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 'Creates an ad plan (campaign)', which is a specific verb+resource. The title 'Create ad plan (campaign)' aligns perfectly, and the sibling list includes 'update_ad_plan' and 'ad_plan_action', making the purpose distinct.

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 mentions that money fields are in account currency and that complex fields should be passed via 'extra'. However, it lacks explicit guidance on when to use this tool versus alternatives like 'update_ad_plan' or 'ad_plan_action', and does not mention any prerequisites or context.

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