Ballast - Cold Email

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add_leads_to_campaign

Add leads from lists or by ID to a cold email campaign while automatically skipping leads already in the campaign, unsubscribed, bounced, suppressed, or invalid.

Instructions

Add leads from lists (or by id) to a campaign Skips leads already in the campaign, unsubscribed, bounced or suppressed leads, and addresses verification found invalid.

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": "add_leads_to_campaign"
  }
}

Input Schema

Name	Required	Description
`id`	Yes
`leadIds`	No
`listIds`	No
`allLeads`	No	Every lead in the workspace

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 21, 2026

TDQS

B3.2/5.0

Behavior3/5

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

With no annotations, the description carries the burden and does disclose meaningful partial-skip semantics: already-in-campaign, unsubscribed, bounced, suppressed, and invalid-address leads are skipped rather than erroring. However, it says nothing about permissions, idempotency, rate limits, or what the response reports about skipped leads.

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

Conciseness4/5

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

A single front-loaded sentence stating the action, then the skip conditions. Slightly run-on with the trailing list of skipped categories, but no padding or repetition.

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

Completeness3/5

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

For a 4-parameter mutation tool with no annotations, no output schema, and 25% schema coverage, the description covers the core action and skip semantics but omits parameter interaction rules and the allLeads option — gaps an agent must guess at.

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 coverage is only 25% (just allLeads), so the schema leaves leadIds and listIds essentially undocumented. The description compensates partially by signaling that leads can come from lists or by id, but it never mentions the allLeads option, the 5000/50 item caps, or whether the source parameters are combinable.

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

Purpose4/5

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

States a specific verb (add) and resource (leads to a campaign) and indicates the two source modes (lists or by id). It is distinguishable from siblings like import_leads, though it never explicitly names or contrasts them.

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

Usage Guidelines2/5

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

No guidance on when to use this versus import_leads or add_suppressions, and no prerequisites or mutual-exclusivity rules for the four source parameters. The only usage-adjacent content is the skip behavior, which is about outcome rather than tool selection.

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