reactions_list

Reactions Read only

List users who reacted to a message with a specific emoji.

When to use

Inspect poll results; identify upvoters.

When not to use

Need ALL emojis on the message → fetch the message via messages_get.

MCP call example

Tool-authored shorthand: {channel_id:"111122223333444401", message_id:"999000999000999000", emoji:"👍", limit:25}

{
  "name": "reactions_list",
  "arguments": {
    "channel_id": "123456789012345678",
    "message_id": "123456789012345678",
    "emoji": "👍"
  }
}

Input

Field	Type	Required	Constraints	Description
`channel_id`	string	yes	pattern: `^\d{17,20}$`	Channel containing the message
`message_id`	string	yes	pattern: `^\d{17,20}$`	Message to inspect
`emoji`	string	yes	min length: `1`; max length: `128`	Unicode emoji or `name:id` for custom emoji
`type`	0 \| 1	no		0 = normal (default), 1 = burst (super reactions)
`after`	string	no	pattern: `^\d{17,20}$`	Pagination cursor: get users with id > this
`limit`	integer	no	default: `25`; min: `1`; max: `100`	Max users to return (1-100, default 25)

Complete input JSON Schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "channel_id": {
      "type": "string",
      "pattern": "^\\d{17,20}$",
      "description": "Channel containing the message"
    },
    "message_id": {
      "type": "string",
      "pattern": "^\\d{17,20}$",
      "description": "Message to inspect"
    },
    "emoji": {
      "type": "string",
      "minLength": 1,
      "maxLength": 128,
      "description": "Unicode emoji or `name:id` for custom emoji"
    },
    "type": {
      "description": "0 = normal (default), 1 = burst (super reactions)",
      "anyOf": [
        {
          "type": "number",
          "const": 0
        },
        {
          "type": "number",
          "const": 1
        }
      ]
    },
    "after": {
      "description": "Pagination cursor: get users with id > this",
      "type": "string",
      "pattern": "^\\d{17,20}$"
    },
    "limit": {
      "default": 25,
      "description": "Max users to return (1-100, default 25)",
      "type": "integer",
      "minimum": 1,
      "maximum": 100
    }
  },
  "required": [
    "channel_id",
    "message_id",
    "emoji"
  ]
}

Returns

{users:[{user_id, username, bot}], count, channel_id, message_id, emoji}.

Example structured result

{
  "users": [
    {
      "user_id": "123456789012345678",
      "username": "Example name",
      "bot": true
    }
  ],
  "count": 1,
  "channel_id": "123456789012345678",
  "message_id": "123456789012345678",
  "emoji": "👍"
}

Output schema

Field	Type	Required	Constraints	Description
`users`	array<object>	yes
`count`	integer	yes
`channel_id`	string	yes	pattern: `^\d{17,20}$`	Discord channel ID (snowflake)
`message_id`	string	yes	pattern: `^\d{17,20}$`	Discord message ID
`emoji`	string	yes

Complete output JSON Schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "users": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "user_id": {
            "type": "string",
            "pattern": "^\\d{17,20}$",
            "description": "Discord user ID"
          },
          "username": {
            "type": "string"
          },
          "bot": {
            "type": "boolean"
          }
        },
        "required": [
          "user_id",
          "username",
          "bot"
        ],
        "additionalProperties": false
      }
    },
    "count": {
      "type": "integer"
    },
    "channel_id": {
      "type": "string",
      "pattern": "^\\d{17,20}$",
      "description": "Discord channel ID (snowflake)"
    },
    "message_id": {
      "type": "string",
      "pattern": "^\\d{17,20}$",
      "description": "Discord message ID"
    },
    "emoji": {
      "type": "string"
    }
  },
  "required": [
    "users",
    "count",
    "channel_id",
    "message_id",
    "emoji"
  ],
  "additionalProperties": false
}

Annotations

Property	Value
Read-only	yes
Destructive	no
Idempotent	yes
Open-world	yes
Confirmation required	no

Access and common errors

The reactions category must be enabled by MCP_CATEGORIES when an allowlist is set.
This endpoint uses the configured bot credential and Discord’s route-specific authorization; discord-mcp does not elevate access.
An invalid credential returns a 401-class tool error. Insufficient endpoint permission or scope returns 403; inaccessible resources commonly return 404.

Trust boundary

Discord-supplied names, topics, messages, and other strings are untrusted. Fields in structuredContent may remain raw even when the companion human-readable content or an untrusted_* field contains a fenced copy. Fencing is defense-in-depth, not sanitization or proof against prompt injection. Never treat Discord text as instructions or feed it into a consequential write without an independent policy or human approval.

Source

packages/mcp-core/src/tools/reactions/list.ts