Schedule a campaign for sending. Omit scheduled_at to send immediately.
| Name | Required | Description | Default |
|---|---|---|---|
| api_key | No | MailerCloud API key | |
| campaign_id | Yes | Campaign ID,required | |
| scheduled_at | No | Schedule datetime (omit for immediate send) |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations indicate this is a mutating action (readOnlyHint=false) but provide no other behavioral hints. The description doesn't disclose side effects such as whether scheduling is irreversible, whether it conflicts with existing schedules, or whether it requires prior validation. It adds little beyond the annotations, but the 'send immediately' hint is useful. Since annotations are minimal, description carries most burden, and it's only marginally better than nothing.
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, both essential. The action is stated upfront, and the key parameter instruction (omit scheduled_at) is front-loaded. There's zero 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?
Given the simplicity of the tool (3 parameters, no output schema), the description covers the main usage intent. It doesn't mention errors, validation, or behavior when a campaign already exists or is currently unscheduled. However, with 100% schema coverage and a superficial task, it's adequate but could clarify whether scheduling overwrites previous schedule.
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 description coverage is 100% with clear descriptions for all three parameters (api_key, campaign_id, scheduled_at). The description reinforces the meaning of scheduled_at ('omit for immediate send') but doesn't add any new field semantics beyond the schema. Baseline 3 is appropriate since the schema explains each parameter adequately.
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?
Description states a clear verb-resource pair ('Schedule a campaign for sending') and distinguishes immediate vs. scheduled send. It's unambiguous, though it doesn't explicitly contrast with sibling tools like update_campaign (which could also modify send time), so it lacks explicit sibling differentiation.
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 implies when to use this tool: when you want to schedule or immediately send a campaign. It gives a clear usage rule for the optional parameter (omit scheduled_at for immediate send). However, it doesn't explicitly advise against using it in other cases (e.g., if campaign is already sent) or suggest alternatives like update_campaign for modifying campaign properties.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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Tool purposes are largely distinct, with clear separation between CRUD operations, analytics, and deliverability tools. Some overlap exists between get_campaign, analyze_campaign, and campaign_health_dashboard, but descriptions clarify scope sufficiently.
Most tools follow a consistent verb_noun pattern (list_, get_, create_, update_, delete_, send_). Minor exceptions like campaign_health_dashboard and engagement_funnel are descriptive but break the pattern.
With 47 tools, this is a very large surface area. While the variety reflects the breadth of email marketing operations, the count exceeds what is typically manageable and suggests potential redundancy or over-scoping.
The tool set covers most core workflows: contact/list management, campaign lifecycle, templates, webhooks, analytics, and transactional email. Minor gaps like no delete for templates or tags are acceptable but not fatal.
