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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds value beyond them by enumerating the returned fields (budget, schedule, status, targeting), which matters because no output schema exists.

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?

A single sentence with zero filler, front-loaded with the verb and resource and ending on the useful payload list. Nothing could be removed without losing information.

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 annotations covering safety and the description listing the payload fields in lieu of an output schema, an agent has what it needs to call this correctly. The main omission is any statement of how it relates to the sibling list/insights tools.

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%, so both domain_id and campaign_id are already documented in the schema. The description's 'by ID' reinforces the lookup key but adds no format, scoping, or error behavior beyond what the schema states; baseline 3 applies.

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 and resource ('Get a single ChatGPT Ads campaign by ID') and enumerates the payload (budget, schedule, status, targeting). The word 'single' plus 'by ID' implicitly separates it from list-openai-ads-campaigns and get-openai-ads-campaign-insights, but neither sibling is named.

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?

Usage is only implied: the agent must infer that this is the right call when it already holds a campaign_id. There is no explicit statement of when to prefer list-openai-ads-campaigns or get-openai-ads-campaign-insights, and no prerequisites (e.g. that domain_id must be resolved first) are mentioned.

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