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messages_compose

Messages Read only

Compose and preview a complete Discord announcement locally: text, typed embeds, uploaded files, polls, and Components V2. Long text and incompatible classic/V2 layouts become ordered message parts.

When to use

Section titled “When to use”

Prepare a rich announcement, tournament post, report, or survey before publishing.

Files

Section titled “Files”

Supply bounded base64 data URIs; preview returns filenames, sizes, and hashes without file bytes.

Next

Section titled “Next”

Present the draft, then call messages_publish with the same fields to obtain its target-bound approval.

MCP call example

Section titled “MCP call example”
{
  "name": "messages_compose",
  "arguments": {
    "content": "Hello from discord-mcp"
  }
}

Input

Section titled “Input”
Field Type Required Constraints Description
content string no max length: 20000
embeds array<object> no max items: 10
components array<unknown> no max items: 40
poll object no
files array<object> no max items: 10
allowed_mentions object no
tts boolean no
Complete input JSON Schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "content": {
      "type": "string",
      "maxLength": 20000
    },
    "embeds": {
      "maxItems": 10,
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "title": {
            "type": "string",
            "maxLength": 256
          },
          "type": {
            "type": "string",
            "const": "rich"
          },
          "description": {
            "type": "string",
            "maxLength": 4096
          },
          "url": {
            "type": "string",
            "format": "uri"
          },
          "timestamp": {
            "type": "string",
            "format": "date-time",
            "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z|([+-](?:[01]\\d|2[0-3]):[0-5]\\d)))$"
          },
          "color": {
            "type": "integer",
            "minimum": 0,
            "maximum": 16777215
          },
          "footer": {
            "type": "object",
            "properties": {
              "text": {
                "type": "string",
                "minLength": 1,
                "maxLength": 2048
              },
              "icon_url": {
                "type": "string"
              }
            },
            "required": [
              "text"
            ],
            "additionalProperties": false
          },
          "image": {
            "type": "object",
            "properties": {
              "url": {
                "type": "string"
              }
            },
            "required": [
              "url"
            ],
            "additionalProperties": false
          },
          "thumbnail": {
            "type": "object",
            "properties": {
              "url": {
                "type": "string"
              }
            },
            "required": [
              "url"
            ],
            "additionalProperties": false
          },
          "author": {
            "type": "object",
            "properties": {
              "name": {
                "type": "string",
                "minLength": 1,
                "maxLength": 256
              },
              "url": {
                "type": "string",
                "format": "uri"
              },
              "icon_url": {
                "type": "string"
              }
            },
            "required": [
              "name"
            ],
            "additionalProperties": false
          },
          "fields": {
            "maxItems": 25,
            "type": "array",
            "items": {
              "type": "object",
              "properties": {
                "name": {
                  "type": "string",
                  "minLength": 1,
                  "maxLength": 256
                },
                "value": {
                  "type": "string",
                  "minLength": 1,
                  "maxLength": 1024
                },
                "inline": {
                  "type": "boolean"
                }
              },
              "required": [
                "name",
                "value"
              ],
              "additionalProperties": false
            }
          }
        },
        "additionalProperties": false
      }
    },
    "components": {
      "maxItems": 40,
      "type": "array",
      "items": {}
    },
    "poll": {
      "type": "object",
      "properties": {
        "question": {
          "type": "object",
          "properties": {
            "text": {
              "type": "string",
              "minLength": 1,
              "maxLength": 300
            }
          },
          "required": [
            "text"
          ],
          "additionalProperties": false
        },
        "answers": {
          "minItems": 2,
          "maxItems": 10,
          "type": "array",
          "items": {
            "type": "object",
            "properties": {
              "poll_media": {
                "type": "object",
                "properties": {
                  "text": {
                    "type": "string",
                    "minLength": 1,
                    "maxLength": 55
                  },
                  "emoji": {
                    "type": "object",
                    "properties": {
                      "id": {
                        "type": "string",
                        "pattern": "^\\d{17,20}$"
                      },
                      "name": {
                        "type": "string",
                        "minLength": 1
                      }
                    },
                    "additionalProperties": false
                  }
                },
                "required": [
                  "text"
                ],
                "additionalProperties": false
              }
            },
            "required": [
              "poll_media"
            ],
            "additionalProperties": false
          }
        },
        "duration": {
          "default": 24,
          "type": "integer",
          "minimum": 1,
          "maximum": 768
        },
        "allow_multiselect": {
          "type": "boolean"
        },
        "layout_type": {
          "default": 1,
          "type": "number",
          "const": 1
        }
      },
      "required": [
        "question",
        "answers"
      ],
      "additionalProperties": false
    },
    "files": {
      "maxItems": 10,
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "filename": {
            "type": "string",
            "pattern": "^[A-Za-z0-9][A-Za-z0-9._-]{0,99}$"
          },
          "data_uri": {
            "type": "string",
            "pattern": "^data:([A-Za-z0-9!#$&^_.+-]+\\/[A-Za-z0-9!#$&^_.+-]+);base64,([A-Za-z0-9+/]*={0,2})$"
          },
          "description": {
            "type": "string",
            "maxLength": 1024
          }
        },
        "required": [
          "filename",
          "data_uri"
        ],
        "additionalProperties": false
      }
    },
    "allowed_mentions": {
      "type": "object",
      "properties": {
        "parse": {
          "default": [],
          "maxItems": 3,
          "type": "array",
          "items": {
            "type": "string",
            "enum": [
              "users",
              "roles",
              "everyone"
            ]
          }
        },
        "users": {
          "maxItems": 100,
          "type": "array",
          "items": {
            "type": "string",
            "pattern": "^\\d{17,20}$"
          }
        },
        "roles": {
          "maxItems": 100,
          "type": "array",
          "items": {
            "type": "string",
            "pattern": "^\\d{17,20}$"
          }
        }
      },
      "additionalProperties": false
    },
    "tts": {
      "type": "boolean"
    }
  }
}

Returns

Section titled “Returns”

{part_count, draft_hash, preview}. No Discord request or write.

Example structured result

Section titled “Example structured result”
{
  "part_count": 1,
  "draft_hash": "example",
  "preview": {}
}

Output schema

Section titled “Output schema”
Field Type Required Constraints Description
part_count integer yes
draft_hash string yes
preview object yes
Complete output JSON Schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "part_count": {
      "type": "integer"
    },
    "draft_hash": {
      "type": "string"
    },
    "preview": {
      "type": "object",
      "propertyNames": {
        "type": "string"
      },
      "additionalProperties": {}
    }
  },
  "required": [
    "part_count",
    "draft_hash",
    "preview"
  ],
  "additionalProperties": false
}

Annotations

Section titled “Annotations”
Property Value
Read-only yes
Destructive no
Idempotent yes
Open-world no
Confirmation required no

Access and common errors

Section titled “Access and common errors”
  • The messages category must be enabled by MCP_CATEGORIES when an allowlist is set.
  • Access contract: scope=local; this tool uses no Discord credential (local or external operation) and is scoped to the local compiler/validator only.
  • No named Discord permission bit is asserted by this contract.
  • Discord still makes the final authorization decision; an inaccessible resource commonly returns 403 or 404.

Source

Section titled “Source”

packages/mcp-core/src/tools/messages/compose.ts

Section titled “Related tools”