Mailcannon

add_campaign_step

Add a sequence step (delay in hours, subject, body)

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": {
      "campaignId": "<campaignId>",
      "day": "<day>",
      "subject": "<subject>",
      "body": "<body>"
    },
    "name": "add_campaign_step"
  }
}

Input Schema

Name	Required	Description
`day`	Yes	Delay in hours
`body`	Yes
`subject`	Yes
`campaignId`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedJul 25, 2026

TDQS

C2.7/5.0

Behavior2/5

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

With no annotations, the description carries the full burden of behavioral disclosure. It only states the action and fields, but does not explain whether the step is appended, what validation occurs, authentication requirements, or what the response looks like. For a mutating tool this is a significant gap.

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?

The description is a single concise sentence that is easy to parse and front-loads the core action. However, it is slightly under-specified and could have used a few more words to clarify the campaign relationship without losing efficiency.

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

Completeness2/5

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

Given there are no annotations and no output schema, the description should explain more about the operation's context, prerequisites, and effects. It omits critical information such as needing an existing campaign, step ordering, and return values, making it incomplete for reliable tool invocation.

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

Parameters2/5

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

Schema description coverage is only 25%, and the description adds minimal clarification beyond the schema (e.g., 'delay in hours' restates the schema's day description). The campaignId parameter is completely unexplained, and subject/body formats are not elaborated. The description does not compensate for the schema's sparse parameter documentation.

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?

The description uses a specific verb ('Add') and identifies the resource ('a sequence step'), with a parenthetical listing the key fields (delay in hours, subject, body). This distinguishes it from update/delete siblings, though it does not explicitly mention the campaign context or how it differs from other add tools.

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 is provided on when to use this tool versus alternatives like update_campaign_step or delete_campaign_step. The only implicit signal is the verb 'Add,' which is not sufficient for an agent to choose this tool confidently.

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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