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

Annotations are present but minimal (readOnly false, destructive false), so the description adds value by noting that campaigns are created in DRAFT by default and that recipientSource='list' is normalized to 'individual'. These are meaningful behavioral traits not disclosed by annotations.

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 two sentences, front-loaded with the primary action, and contains no redundant filler. Every sentence adds either scope clarification or config guidance.

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 8 parameters, nested channelConfig, and an output schema, the description covers key behavior: supported channels, default status, and alias handling. It does not explicitly mention scheduling or segment/recipient options, but the schema documents those thoroughly, making the description adequate.

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 covers all parameters (100%), giving a baseline of 3. The description adds specific guidance for email channelConfig ('subject + htmlBody + optional plainTextBody') and reiterates the alias behavior, which is slightly more detailed than the schema's existing description of 'normalized to individual'.

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 'Create a marketing campaign (email, SMS, or WhatsApp) in DRAFT.' This clearly identifies the verb ('Create'), resource ('marketing campaign'), and scope (supported channels and default status). It distinguishes the tool from siblings like create_broadcast and create_template by specifying campaign creation.

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 gives usage details for email channelConfig and clarifies the recipientSource alias, but does not explicitly state when to use this tool versus alternatives like create_broadcast or update_campaign. The usage context is implied rather than directly contrasted with sibling tools.

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