Fluxmail

Create draft

create_draft

Compose and save email drafts in connected mailboxes; reply to an existing message to auto-fill recipients and subject, or reply to all.

Instructions

Create a draft in the mailbox. With replyToMessageId, the draft is a reply: recipients and a subject left out come from the original message, and replyAll includes all of its recipients.

Input Schema

Name	Required	Description
`cc`	No	Recipients, each "Name <a@x.com>" or "a@x.com"
`to`	No	Recipients, each "Name <a@x.com>" or "a@x.com"
`bcc`	No	Recipients, each "Name <a@x.com>" or "a@x.com"
`from`	No	Connected address or an available send-as address
`subject`	No	Defaults to "Re: ..." when replying
`bodyHtml`	No	HTML body
`bodyText`	No	Plain-text body. Line breaks appear in the sent email. Keep each prose paragraph on one continuous line and separate paragraphs with blank lines.
`replyAll`	No	With replyToMessageId: reply to all original recipients
`accountId`	No	Account to operate on. Optional when exactly one account is connected.
`attachments`	No
`replyToMessageId`	No	Message being replied to; threads correctly and computes recipients if "to" is omitted

Output Schema

Name	Required	Description	Default
`data`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed8 schema fields changedv0.19.0Oct 30, 2026

changedInput schema / properties / accountId / anyOf

Previous value: -[
-  {
-    "minLength": 1,
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "maxLength": 512,
+    "minLength": 1,
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

changedInput schema / properties / attachments / anyOf

Previous value: -[
-  {
-    "items": {
-      "additionalProperties": false,
-      "properties": {
-        "content": {
-          "description": "base64",
-          "type": "string"
-        },
-        "contentId": {
-          "description": "Content-ID for an inline image, referenced from bodyHtml as cid:<contentId>",
-          "minLength": 1,
-          "type": "string"
-        },
-        "disposition": {
-          "description": "Defaults to attachment",
-          "enum": [
-            "inline",
-            "attachment"
-          ],
-          "type": "string"
-        },
-        "filename": {
-          "minLength": 1,
-          "type": "string"
-        },
-        "mimeType": {
-          "minLength": 1,
-          "type": "string"
-        }
-      },
-      "required": [
-        "filename",
-        "mimeType",
-        "content"
-      ],
-      "type": "object"
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "items": {
+      "additionalProperties": false,
+      "properties": {
+        "content": {
+          "description": "base64",
+          "type": "string"
+        },
+        "contentId": {
+          "description": "Content-ID for an inline image, referenced from bodyHtml as cid:<contentId>",
+          "maxLength": 255,
+          "minLength": 1,
+          "type": "string"
+        },
+        "disposition": {
+          "description": "Defaults to attachment",
+          "enum": [
+            "inline",
+            "attachment"
+          ],
+          "type": "string"
+        },
+        "filename": {
+          "maxLength": 255,
+          "minLength": 1,
+          "type": "string"
+        },
+        "mimeType": {
+          "maxLength": 255,
+          "minLength": 1,
+          "type": "string"
+        }
+      },
+      "required": [
+        "filename",
+        "mimeType",
+        "content"
+      ],
+      "type": "object"
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

changedInput schema / properties / bcc / anyOf

Previous value: -[
-  {
-    "description": "Recipients, each \"Name <a@x.com>\" or \"a@x.com\"",
-    "items": {
-      "minLength": 1,
-      "type": "string"
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "description": "Recipients, each \"Name <a@x.com>\" or \"a@x.com\"",
+    "items": {
+      "maxLength": 512,
+      "minLength": 1,
+      "type": "string"
+    },
+    "maxItems": 100,
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

changedInput schema / properties / cc / anyOf

Previous value: -[
-  {
-    "description": "Recipients, each \"Name <a@x.com>\" or \"a@x.com\"",
-    "items": {
-      "minLength": 1,
-      "type": "string"
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "description": "Recipients, each \"Name <a@x.com>\" or \"a@x.com\"",
+    "items": {
+      "maxLength": 512,
+      "minLength": 1,
+      "type": "string"
+    },
+    "maxItems": 100,
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

changedInput schema / properties / replyToMessageId / anyOf

Previous value: -[
-  {
-    "minLength": 1,
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "maxLength": 512,
+    "minLength": 1,
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

addedInput schema / properties / subject / anyOf

Added value: +[
+  {
+    "maxLength": 998,
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

removedInput schema / properties / subject / type
```
Removed value: -[
-  "string",
-  "null"
-]
```

changedInput schema / properties / to / anyOf

Previous value: -[
-  {
-    "description": "Recipients, each \"Name <a@x.com>\" or \"a@x.com\"",
-    "items": {
-      "minLength": 1,
-      "type": "string"
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "description": "Recipients, each \"Name <a@x.com>\" or \"a@x.com\"",
+    "items": {
+      "maxLength": 512,
+      "minLength": 1,
+      "type": "string"
+    },
+    "maxItems": 100,
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

Changed3 schema fields changedv0.18.0Oct 28, 2026

changedInput schema / properties / attachments / anyOf

Previous value: -[
-  {
-    "items": {
-      "additionalProperties": false,
-      "properties": {
-        "content": {
-          "description": "base64",
-          "type": "string"
-        },
-        "filename": {
-          "minLength": 1,
-          "type": "string"
-        },
-        "mimeType": {
-          "minLength": 1,
-          "type": "string"
-        }
-      },
-      "required": [
-        "filename",
-        "mimeType",
-        "content"
-      ],
-      "type": "object"
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "items": {
+      "additionalProperties": false,
+      "properties": {
+        "content": {
+          "description": "base64",
+          "type": "string"
+        },
+        "contentId": {
+          "description": "Content-ID for an inline image, referenced from bodyHtml as cid:<contentId>",
+          "minLength": 1,
+          "type": "string"
+        },
+        "disposition": {
+          "description": "Defaults to attachment",
+          "enum": [
+            "inline",
+            "attachment"
+          ],
+          "type": "string"
+        },
+        "filename": {
+          "minLength": 1,
+          "type": "string"
+        },
+        "mimeType": {
+          "minLength": 1,
+          "type": "string"
+        }
+      },
+      "required": [
+        "filename",
+        "mimeType",
+        "content"
+      ],
+      "type": "object"
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

changedInput schema / properties / bcc / anyOf

Previous value: -[
-  {
-    "$ref": "#/properties/to/anyOf/0"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "description": "Recipients, each \"Name <a@x.com>\" or \"a@x.com\"",
+    "items": {
+      "minLength": 1,
+      "type": "string"
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

changedInput schema / properties / cc / anyOf

Previous value: -[
-  {
-    "$ref": "#/properties/to/anyOf/0"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "description": "Recipients, each \"Name <a@x.com>\" or \"a@x.com\"",
+    "items": {
+      "minLength": 1,
+      "type": "string"
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

Changed23 schema fields changedv0.15.0Oct 17, 2026

addedInput schema / properties / accountId / anyOf

Added value: +[
+  {
+    "minLength": 1,
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

removedInput schema / properties / accountId / minLength
```
Removed value: -1
```
removedInput schema / properties / accountId / type
```
Removed value: -"string"
```

addedInput schema / properties / attachments / anyOf

Added value: +[
+  {
+    "items": {
+      "additionalProperties": false,
+      "properties": {
+        "content": {
+          "description": "base64",
+          "type": "string"
+        },
+        "filename": {
+          "minLength": 1,
+          "type": "string"
+        },
+        "mimeType": {
+          "minLength": 1,
+          "type": "string"
+        }
+      },
+      "required": [
+        "filename",
+        "mimeType",
+        "content"
+      ],
+      "type": "object"
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

removedInput schema / properties / attachments / items

Removed value: -{
-  "additionalProperties": false,
-  "properties": {
-    "content": {
-      "description": "base64",
-      "type": "string"
-    },
-    "filename": {
-      "minLength": 1,
-      "type": "string"
-    },
-    "mimeType": {
-      "minLength": 1,
-      "type": "string"
-    }
-  },
-  "required": [
-    "filename",
-    "mimeType",
-    "content"
-  ],
-  "type": "object"
-}

removedInput schema / properties / attachments / type
```
Removed value: -"array"
```
removedInput schema / properties / bcc / $ref
```
Removed value: -"#/properties/to"
```

addedInput schema / properties / bcc / anyOf

Added value: +[
+  {
+    "$ref": "#/properties/to/anyOf/0"
+  },
+  {
+    "type": "null"
+  }
+]

changedInput schema / properties / bodyHtml / type

Previous value: -"string"New value: +[
+  "string",
+  "null"
+]

changedInput schema / properties / bodyText / type

Previous value: -"string"New value: +[
+  "string",
+  "null"
+]

removedInput schema / properties / cc / $ref
```
Removed value: -"#/properties/to"
```

addedInput schema / properties / cc / anyOf

Added value: +[
+  {
+    "$ref": "#/properties/to/anyOf/0"
+  },
+  {
+    "type": "null"
+  }
+]

addedInput schema / properties / from / anyOf

Added value: +[
+  {
+    "format": "email",
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

removedInput schema / properties / from / format
```
Removed value: -"email"
```
removedInput schema / properties / from / type
```
Removed value: -"string"
```

changedInput schema / properties / replyAll / type

Previous value: -"boolean"New value: +[
+  "boolean",
+  "null"
+]

addedInput schema / properties / replyToMessageId / anyOf

Added value: +[
+  {
+    "minLength": 1,
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

removedInput schema / properties / replyToMessageId / minLength
```
Removed value: -1
```
removedInput schema / properties / replyToMessageId / type
```
Removed value: -"string"
```

changedInput schema / properties / subject / type

Previous value: -"string"New value: +[
+  "string",
+  "null"
+]

addedInput schema / properties / to / anyOf

Added value: +[
+  {
+    "description": "Recipients, each \"Name <a@x.com>\" or \"a@x.com\"",
+    "items": {
+      "minLength": 1,
+      "type": "string"
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

removedInput schema / properties / to / items

Removed value: -{
-  "minLength": 1,
-  "type": "string"
-}

removedInput schema / properties / to / type
```
Removed value: -"array"
```

Changed1 schema field changedv0.11.1Oct 1, 2026
- removedOutput schema / $schema
```
Removed value: -"http://json-schema.org/draft-07/schema#"
```

Changed2 schema fields changedv0.11.0Sep 26, 2026

changedInput schema / properties / bodyText / description

Previous value: -"Plain-text body"New value: +"Plain-text body. Line breaks appear in the sent email. Keep each prose paragraph on one continuous line and separate paragraphs with blank lines."

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "data": {
+      "additionalProperties": true,
+      "properties": {
+        "accountId": {
+          "type": "string"
+        },
+        "attachments": {
+          "items": {
+            "additionalProperties": true,
+            "properties": {
+              "filename": {
+                "type": "string"
+              },
+              "id": {
+                "type": "string"
+              },
+              "mimeType": {
+                "type": "string"
+              },
+              "sizeBytes": {
+                "type": "number"
+              }
+            },
+            "required": [
+              "id",
+              "filename",
+              "mimeType",
+              "sizeBytes"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "body": {
+          "additionalProperties": false,
+          "properties": {
+            "html": {
+              "type": "string"
+            },
+            "text": {
+              "type": "string"
+            }
+          },
+          "type": "object"
+        },
+        "bodyTruncation": {
+          "additionalProperties": {
+            "additionalProperties": false,
+            "properties": {
+              "nextOffset": {
+                "type": "number"
+              },
+              "totalChars": {
+                "type": "number"
+              }
+            },
+            "required": [
+              "totalChars"
+            ],
+            "type": "object"
+          },
+          "type": "object"
+        },
+        "date": {
+          "type": "string"
+        },
+        "flags": {
+          "additionalProperties": true,
+          "properties": {
+            "draft": {
+              "type": "boolean"
+            },
+            "read": {
+              "type": "boolean"
+            },
+            "starred": {
+              "type": "boolean"
+            }
+          },
+          "required": [
+            "read",
+            "starred",
+            "draft"
+          ],
+          "type": "object"
+        },
+        "id": {
+          "type": "string"
+        },
+        "subject": {
+          "type": "string"
+        },
+        "threadId": {
+          "type": "string"
+        },
+        "to": {
+          "items": {
+            "additionalProperties": true,
+            "properties": {
+              "email": {
+                "type": "string"
+              },
+              "name": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "email"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        }
+      },
+      "required": [
+        "id",
+        "threadId",
+        "accountId",
+        "to",
+        "subject",
+        "date",
+        "flags"
+      ],
+      "type": "object"
+    }
+  },
+  "required": [
+    "data"
+  ],
+  "type": "object"
+}

Changed1 schema field changedv0.9.0Sep 16, 2026

addedInput schema / properties / from

Added value: +{
+  "description": "Connected address or an available send-as address",
+  "format": "email",
+  "type": "string"
+}

First observedv0.1.0Jul 26, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already declare non-destructive, non-idempotent, closed-world behavior, so the bar is lower. The description adds genuine non-schema context: omitted recipients and subject are inherited from the original message when replyToMessageId is set, and replyAll expands to all original recipients. It stops short of stating where the draft lands or that nothing is transmitted.

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?

Two sentences, front-loaded with the core action before the conditional reply behavior. Nothing is padded and the conditional is clearly marked by "With replyToMessageId".

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?

With 11 all-optional parameters and an output schema present, the description needn't explain return values, and the reply path — the least obvious usage mode — is well covered. The attachment and send-as paths are undocumented in prose, but the schema carries them at 91% coverage.

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

Parameters4/5

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

Schema coverage is 91%, so the baseline is 3, and the description earns a bump by explaining the interaction between replyToMessageId, omitted to/subject, and replyAll — cross-parameter semantics the schema documents only per-field. Attachments, from/send-as, and accountId are left entirely to the schema.

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 first sentence names a specific verb and resource ("Create a draft in the mailbox") and the second immediately scopes the reply variant. An agent can tell this apart from update_draft, get_draft, and send_email without consulting any schema.

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 only implied: creating a draft rather than sending is inferable from the verb and the sibling names, and the reply branch is described in detail. But there is no explicit statement of when to prefer this over send_email or update_draft, and no prerequisites or exclusions are given.

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