Ballast - Cold Email

Add mailbox

add_mailbox

Connect a mailbox. Tests SMTP and IMAP login first and saves only when both pass. Google needs an app password. Microsoft 365 connects with OAuth from the dashboard.

Input Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedOct 21, 2026

addedInput schema / oneOf

Added value: +[
+  {
+    "properties": {
+      "dailyLimit": {
+        "default": 30,
+        "maximum": 500,
+        "minimum": 1,
+        "type": "integer"
+      },
+      "displayName": {
+        "maxLength": 120,
+        "type": "string"
+      },
+      "email": {
+        "type": "string"
+      },
+      "password": {
+        "maxLength": 64,
+        "minLength": 1,
+        "type": "string"
+      },
+      "provider": {
+        "const": "google_app",
+        "type": "string"
+      }
+    },
+    "required": [
+      "provider",
+      "email",
+      "password"
+    ],
+    "type": "object"
+  },
+  {
+    "properties": {
+      "dailyLimit": {
+        "default": 30,
+        "maximum": 500,
+        "minimum": 1,
+        "type": "integer"
+      },
+      "displayName": {
+        "maxLength": 120,
+        "type": "string"
+      },
+      "email": {
+        "type": "string"
+      },
+      "imap": {
+        "properties": {
+          "host": {
+            "maxLength": 253,
+            "minLength": 1,
+            "pattern": "^[a-z0-9.-]+$",
+            "type": "string"
+          },
+          "port": {
+            "maximum": 65535,
+            "minimum": 1,
+            "type": "integer"
+          },
+          "security": {
+            "enum": [
+              "tls",
+              "starttls"
+            ],
+            "type": "string"
+          },
+          "user": {
+            "maxLength": 320,
+            "minLength": 1,
+            "type": "string"
+          }
+        },
+        "required": [
+          "host",
+          "port",
+          "security",
+          "user"
+        ],
+        "type": "object"
+      },
+      "password": {
+        "maxLength": 512,
+        "minLength": 1,
+        "type": "string"
+      },
+      "provider": {
+        "const": "smtp",
+        "type": "string"
+      },
+      "smtp": {
+        "properties": {
+          "host": {
+            "maxLength": 253,
+            "minLength": 1,
+            "pattern": "^[a-z0-9.-]+$",
+            "type": "string"
+          },
+          "port": {
+            "maximum": 65535,
+            "minimum": 1,
+            "type": "integer"
+          },
+          "security": {
+            "enum": [
+              "tls",
+              "starttls"
+            ],
+            "type": "string"
+          },
+          "user": {
+            "maxLength": 320,
+            "minLength": 1,
+            "type": "string"
+          }
+        },
+        "required": [
+          "host",
+          "port",
+          "security",
+          "user"
+        ],
+        "type": "object"
+      }
+    },
+    "required": [
+      "provider",
+      "email",
+      "password",
+      "smtp",
+      "imap"
+    ],
+    "type": "object"
+  }
+]

removedInput schema / properties

Removed value: -{
-  "input": {
-    "oneOf": [
-      {
-        "properties": {
-          "dailyLimit": {
-            "default": 30,
-            "maximum": 500,
-            "minimum": 1,
-            "type": "integer"
-          },
-          "displayName": {
-            "maxLength": 120,
-            "type": "string"
-          },
-          "email": {
-            "type": "string"
-          },
-          "password": {
-            "maxLength": 64,
-            "minLength": 1,
-            "type": "string"
-          },
-          "provider": {
-            "const": "google_app",
-            "type": "string"
-          }
-        },
-        "required": [
-          "provider",
-          "email",
-          "password"
-        ],
-        "type": "object"
-      },
-      {
-        "properties": {
-          "dailyLimit": {
-            "default": 30,
-            "maximum": 500,
-            "minimum": 1,
-            "type": "integer"
-          },
-          "displayName": {
-            "maxLength": 120,
-            "type": "string"
-          },
-          "email": {
-            "type": "string"
-          },
-          "imap": {
-            "properties": {
-              "host": {
-                "maxLength": 253,
-                "minLength": 1,
-                "pattern": "^[a-z0-9.-]+$",
-                "type": "string"
-              },
-              "port": {
-                "maximum": 65535,
-                "minimum": 1,
-                "type": "integer"
-              },
-              "security": {
-                "enum": [
-                  "tls",
-                  "starttls"
-                ],
-                "type": "string"
-              },
-              "user": {
-                "maxLength": 320,
-                "minLength": 1,
-                "type": "string"
-              }
-            },
-            "required": [
-              "host",
-              "port",
-              "security",
-              "user"
-            ],
-            "type": "object"
-          },
-          "password": {
-            "maxLength": 512,
-            "minLength": 1,
-            "type": "string"
-          },
-          "provider": {
-            "const": "smtp",
-            "type": "string"
-          },
-          "smtp": {
-            "properties": {
-              "host": {
-                "maxLength": 253,
-                "minLength": 1,
-                "pattern": "^[a-z0-9.-]+$",
-                "type": "string"
-              },
-              "port": {
-                "maximum": 65535,
-                "minimum": 1,
-                "type": "integer"
-              },
-              "security": {
-                "enum": [
-                  "tls",
-                  "starttls"
-                ],
-                "type": "string"
-              },
-              "user": {
-                "maxLength": 320,
-                "minLength": 1,
-                "type": "string"
-              }
-            },
-            "required": [
-              "host",
-              "port",
-              "security",
-              "user"
-            ],
-            "type": "object"
-          }
-        },
-        "required": [
-          "provider",
-          "email",
-          "password",
-          "smtp",
-          "imap"
-        ],
-        "type": "object"
-      }
-    ]
-  }
-}

removedInput schema / required
```
Removed value: -[
-  "input"
-]
```

First observedOct 21, 2026

TDQS

A3.8/5.0

Behavior4/5

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

The description discloses important behavior beyond annotations: credentials are tested via SMTP and IMAP login first, and the mailbox is saved only if both pass. It also notes provider-specific authentication requirements. This is strong transparency for a non-read-only, open-world mutation tool.

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 four short sentences, front-loaded with the core action and followed by validation behavior and provider prerequisites. Every sentence adds useful information without repetition or filler.

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 tool with a rich oneOf schema and no output schema, the description supplies the most important non-schema behavior: login validation and provider auth caveats. It could be slightly more complete by clarifying that SMTP connections require explicit SMTP/IMAP server settings, but the schema covers those details.

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 the schema already carries most parameter documentation. The description adds provider-specific context for Google and Microsoft 365, but it does not explain fields such as dailyLimit, displayName, or the smtp/imap nested settings beyond what the schema already provides.

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 states a specific verb and resource: 'Connect a mailbox.' It adds meaningful scope about validating SMTP and IMAP login before saving, but it does not explicitly differentiate this tool from siblings such as list_mailboxes or add_domain.

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?

It gives provider-specific prerequisites, notably Google app passwords and Microsoft 365 OAuth via the dashboard. However, it does not explicitly say when to use this tool versus alternatives or when not to use it, so usage guidance is present but implicit.

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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