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

The description discloses a critical behavior: 'Creating never sends' and that the campaign is created as a draft. This adds context beyond the annotations (which only indicate non-read-only, non-idempotent, non-destructive) and clarifies the lack of immediate sending 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?

The description is extremely concise—two sentences—and clearly conveys the core purpose and the key behavior (no sending). It avoids superfluous words and is well-structured for quick understanding.

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?

For a create operation with no output schema, the description adequately explains that it creates a draft and does not send, but it omits details about the return value (e.g., campaign ID) and any expected side effects. Given the tool's simplicity, this is acceptable but not highly 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?

The schema already provides per-parameter descriptions covering all 11 parameters (100% coverage), and the overall description does not add granular details about parameters. It only generically refers to 'content and audience,' which is already implied by the schema. Thus, it adds minimal value beyond the schema.

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 'Create a new email marketing campaign as a draft' and explicitly distinguishes it from sending by noting 'Creating never sends — call send_campaign separately.' This makes the purpose unambiguous and differentiates it from the sibling tool send_campaign.

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?

It provides clear guidance to call send_campaign separately once content and audience are confirmed, implying the intended workflow. However, it does not explicitly mention when not to use other related tools (e.g., list_campaigns, update_campaign), but given the context, the guidance is sufficient.

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