Mailchimp MCP Server

mailchimp_ecommerce_customers_add

Add a customer to a Mailchimp ecommerce store by providing store ID, unique customer ID, email address, and marketing opt-in status.

Instructions

Add a new customer

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": {
      "store_id": "<store_id>",
      "id": "<id>",
      "email_address": "<email_address>",
      "opt_in_status": "<opt_in_status>"
    },
    "name": "mailchimp_ecommerce_customers_add"
  }
}

Input Schema

Name	Required	Description
`id`	Yes	Unique customer ID
`company`	No	Company name
`store_id`	Yes	Store ID
`last_name`	No	Last name
`first_name`	No	First name
`email_address`	Yes	Email address
`opt_in_status`	Yes	Marketing opt-in status

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 2, 2026

TDQS

C2.6/5.0

Behavior1/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It only says 'Add a new customer' with no mention of idempotency, overwrite behavior, required parent resources, or any side effects. This is a creation operation but the description provides no behavioral context beyond the verb 'Add'.

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, focused sentence that is easy to parse and front-loaded. It is not bloated, though it is so minimal that it borders on under-specification rather than effective conciseness.

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

Completeness1/5

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

This is a creation tool with 7 parameters, no annotations, and no output schema. The description provides no context about required fields, relationship to stores or other ecommerce resources, error conditions, or return values. It is inadequate for an agent to safely and effectively use the tool.

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 100%, so all seven parameters have descriptions that define their meaning. The tool description itself adds no additional parameter context, but the baseline of 3 is appropriate because the schema already documents each field clearly (e.g., 'opt_in_status' as 'Marketing opt-in status').

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 'Add a new customer' clearly states the action (add) and resource (customer), which is a specific verb+resource pair. However, it does not explicitly distinguish this ecommerce customer tool from the sibling mailchimp_members_add, which also adds a customer/member to an audience; the name 'ecommerce_customers_add' provides the differentiation but the description alone is generic.

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?

There is no guidance on when to use this tool versus alternatives like mailchimp_members_add or mailchimp_ecommerce_customers_update. The description only states what it does, with no mention of prerequisites (e.g., store must already exist) or contexts where it should be preferred.

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

Deploy Server