Ballast - Cold Email

Preview campaign

preview_campaign

Read-only

Render every step and variant for one lead. Shows the emails exactly as that lead would get them, with spintax resolved the way it will be for them. Defaults to the first lead in the campaign.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "id": "<id>"
    },
    "name": "preview_campaign"
  }
}

Input Schema

Name	Required	Description	Default
`id`	Yes
`leadId`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 21, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so safety is covered. The description adds useful behavioral context beyond annotations: it renders every step and variant, resolves spintax as it will appear for the lead, and defaults to the first campaign lead.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is three tight sentences with zero waste. The core action is front-loaded in the first sentence, followed by a clarifying detail and the default behavior.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple read-only preview tool with no output schema and only two parameters, the description is mostly complete: it explains what is rendered, how spintax is handled, and the default lead behavior. The main remaining gap is not explicitly naming the required id as the campaign identifier.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must carry parameter meaning. It explains that preview is for one lead and that the lead defaults to the first lead in the campaign, which gives useful semantics for leadId, but it does not explicitly clarify that the required id parameter is the campaign identifier.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: 'Render every step and variant for one lead.' It also clarifies that it shows emails exactly as that lead would receive them with spintax resolved, which clearly distinguishes this preview tool from sibling campaign tools like get_campaign or update_campaign.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied rather than explicitly guided: the description says it defaults to the first lead in the campaign, which helps an agent understand optional behavior. However, it does not state when to use this tool instead of alternatives such as get_campaign, write_sequence, or launch_campaign.

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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