Cancel a scheduled or in-flight email campaign to stop further sends, while messages already queued remain unaffected. Use this to halt campaigns before they reach more recipients.
Cancel a scheduled or in-flight campaign. Messages already queued are not recalled.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Numeric campaign id |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already carry destructiveHint: true, but the description adds meaningful behavioral context on top: 'Messages already queued are not recalled' clarifies the boundary of the destructive effect. This goes beyond what the structured hint conveys and warns the agent about an irreversible partial outcome.
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?
Two sentences with zero filler: the action is front-loaded and the critical caveat follows immediately. Every word earns its place.
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 single-parameter operation with annotations and full schema coverage, the description captures the essential behavioral caveat. It omits a note on the outcome/return value, but with no output schema present and the tool being simple, nothing an agent needs to invoke it correctly is missing.
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% and the id parameter is fully documented in the schema ('Numeric campaign id' with exclusiveMinimum). The description adds nothing about the parameter itself, so the baseline 3 is appropriate.
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 (Cancel), resource (campaign), and scope (scheduled or in-flight), which clearly distinguishes this tool from siblings like send_campaign_now, update_campaign, or archive_stream. An agent can identify what this tool does without opening the schema.
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 phrase 'scheduled or in-flight' implies when the tool is appropriate, but the description never says when not to use it or names an alternative (e.g., update_campaign for editing, or pausing differently). Usage context is implied rather than explicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.