Join Channel

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Overview

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Channel-Based Communication

1. WebSocket Relay - Routes messages between the MCP server and Figma plugin
2. Channels - Logical communication spaces that isolate different sessions
3. Plugin Connection - Each Figma plugin instance joins a specific channel

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Usage

// First command in any session
const result = await mcp.use_mcp_tool({
  server_name: "TalkToFigma",
  tool_name: "join_channel",
  arguments: {
    channel: "my-design-session"
  }
});

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Parameters

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Response

Successfully joined channel: {channel}

• Not connected to WebSocket server
• Invalid channel name
• Connection issues

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Workflow

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Step 1: Start WebSocket Relay

bun socket

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Step 2: Configure Figma Plugin

1. Open the Talk to Figma plugin in Figma
2. Enter the channel name (e.g., my-session)
3. Click “Connect”

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Step 3: Join from MCP

await mcp.use_mcp_tool({
  server_name: "TalkToFigma",
  tool_name: "join_channel",
  arguments: {
    channel: "my-session"  // Must match Figma plugin
  }
});

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Step 4: Execute Commands

// Now you can execute Figma commands
const doc = await mcp.use_mcp_tool({
  server_name: "TalkToFigma",
  tool_name: "get_document_info",
  arguments: {}
});

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Channel Isolation

• Commands sent on channel-a only reach plugins connected to channel-a
• Different channels can operate on different Figma files simultaneously
• Channel switching requires calling join_channel again

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Common Errors

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”Not connected to Figma”

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”Must join a channel before sending commands”

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No response from Figma

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Architecture

AI Agent (Claude/Cursor)
       ↓ stdio
MCP Server (Node.js)
       ↓ WebSocket
Relay Server (port 3055)
       ↓ WebSocket + Channel
Figma Plugin
       ↓ Plugin API
Figma Document

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Related Tools

• get_document_info - First command after joining
• get_selection - Check current selection