campaign_countries_preview

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

Annotations already declare this as read-only, idempotent, non-destructive, and open-world. The description adds that the tool previews country-targeting replacement, but it does not explain what the preview evaluates, what constraints apply, or what the agent should do with the result.

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 front-loaded sentence with no wasted text. However, its terseness leaves the action and effect of "replacing" somewhat ambiguous.

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?

An output schema exists and annotations provide the safety profile, reducing what the description must cover. Still, with four required parameters and only partial schema descriptions, the description lacks enough usage and parameter context to be fully complete.

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 only 50%, and the description does not compensate by explaining the undescribed parameters. It only indirectly references the countries parameter through "country targeting" and gives no added detail for campaignId or countries format.

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 uses a specific verb, "Preview," and identifies the resource as campaign country targeting. It is clear enough to distinguish this tool from general campaign previews, but it does not explicitly differentiate itself from related campaign preview tools such as campaign_update_preview.

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?

There is no explicit guidance on when to use this tool versus alternatives, nor any stated prerequisites or exclusions. The agent must infer that it should be used before changing campaign country targeting.

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