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

The annotations already establish this as a non-read-only update. The description adds important behavior beyond the annotations: only sent fields change, and steps are replaced wholesale, so preserving an existing step requires sending its id. That is meaningful mutation behavior, though it does not cover permissions or failure behavior.

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, front-loaded with the changed fields and followed by the two most important invocation caveats. There is no visible filler.

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?

The tool has a full output schema and annotations, so the description does not need to explain return values or safety. It covers the main mutation gotchas: partial field updates and step replacement. It is slightly thin on when to choose this update tool over sibling campaign operations.

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?

With 60% schema coverage, the description compensates for the missing top-level steps guidance by explaining that steps replaces every step and that an existing step must include its id to keep personalization and past versions. Other parameters are mostly covered by the schema, and the description does not add much beyond them.

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: changing a campaign’s name, steps, sender pool, or daily limit. It is clear what the tool modifies, but it does not explicitly contrast itself with sibling tools such as campaigns_set_status or campaigns_add_recipients.

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 says what can be changed but gives no explicit guidance on when to use this tool versus alternatives. It also omits prerequisites or exclusions, leaving the agent to infer usage from the name and schema.

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