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

Beyond the readOnlyHint annotation, the description discloses important behavioral nuances: adScheduleStructured is canonical, adSchedule is a legacy echo, timezone semantics, and the Microsoft-only searcher timezone flag. It also clarifies that scoping defaults to the active Space and can be overridden, which is essential operational knowledge.

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 well-structured, front-loaded with the core purpose, and uses subsequent sentences for schedule field clarifications and scoping. It is slightly dense with adSchedule technical details, but each sentence contributes meaningful information and there is no fluff.

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 no output schema, the description takes on the burden of explaining return value nuances. It thoroughly covers the tricky adSchedule fields, timezone behavior, and Space scoping, leaving little ambiguity for the agent. The only omission is error/not-found behavior, but that is not critical for a get-by-id tool.

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 for parameters is 100%, with detailed descriptions for both campaign_id and space_id. The tool description does not add new parameter-level semantics beyond what the schema already states; it merely restates the scoping override concept. This meets the baseline for full schema coverage.

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 opens with a specific verb and resource: "Fetch one campaign by id." It clearly differentiates from sibling tools like list_campaigns and get_campaign_asset by focusing on a single campaign object retrieval. The mention of returning "the full campaign object" further reinforces its singular scope.

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 explains the active Space scoping and explicitly points to set_active_space and the optional space_id override for one-off calls. It does not explicitly contrast with list_campaigns, but the context implies use cases for fetching a single known campaign.

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