charleswiltgen/axiom-xcode-mcp-setup

Xcode MCP Setup

Prerequisites

• Xcode 26.3+ with MCP support
• macOS with Xcode installed and running
• At least one project/workspace open in Xcode

Step 1: Enable MCP in Xcode

1. Open Xcode Settings (Cmd+,)
2. Go to Intelligence tab
3. Check Enable Model Context Protocol
4. Ensure Xcode Tools toggle is ON

Without this toggle, xcrun mcpbridge connects but returns no tools.

Step 2: Connect Your MCP Client

Claude Code

claude mcp add --transport stdio xcode -- xcrun mcpbridge

Verify: claude mcp list should show xcode server.

Codex

codex mcp add xcode -- xcrun mcpbridge

Cursor

Create or edit .cursor/mcp.json in your project root:

{
  "mcpServers": {
    "xcode": {
      "command": "xcrun",
      "args": ["mcpbridge"]
    }
  }
}

Cursor-specific note: Cursor is a strict MCP client. Xcode's mcpbridge omits structuredContent when tools declare outputSchema, which violates the MCP spec. If Cursor rejects responses, use XcodeMCPWrapper as a proxy:

{
  "mcpServers": {
    "xcode": {
      "command": "/path/to/XcodeMCPWrapper",
      "args": []
    }
  }
}

VS Code + GitHub Copilot

Create or edit .vscode/mcp.json:

{
  "servers": {
    "xcode": {
      "type": "stdio",
      "command": "xcrun",
      "args": ["mcpbridge"]
    }
  }
}

Gemini CLI

gemini mcp add xcode -- xcrun mcpbridge

Step 3: Verify Connection

After configuration, call XcodeListWindows (no parameters). You should see:

tabIdentifier: <uuid>, workspacePath: /path/to/YourProject.xcodeproj

If you see an empty list, ensure a project is open in Xcode.

Permission Dialog

When an MCP client first connects, Xcode shows a permission dialog:

• Identifies the connecting process by PID
• Asks to allow MCP tool access
• Must be approved in Xcode's UI (not terminal)

PID-based approval: Permission is granted per-process. If the client restarts (new PID), you'll see the dialog again. This is expected behavior.

Multi-Xcode Targeting

When multiple Xcode instances are running:

Auto-Detection (default)

mcpbridge auto-selects using this fallback:

1. If exactly one Xcode process is running → uses that
2. If multiple → uses the one matching xcode-select
3. If none → exits with error

Manual PID Selection

Set MCP_XCODE_PID to target a specific instance:

# Find Xcode PIDs
pgrep -x Xcode

# Claude Code with specific PID
claude mcp add --transport stdio xcode -- env MCP_XCODE_PID=12345 xcrun mcpbridge

Session ID (optional)

MCP_XCODE_SESSION_ID provides a stable UUID for tool sessions, useful when tracking interactions across reconnections.

Troubleshooting

digraph troubleshoot {
    rankdir=TB;
    "Connection failed?" [shape=diamond];
    "tools/list empty?" [shape=diamond];
    "Wrong project?" [shape=diamond];
    "Repeated permission prompts?" [shape=diamond];
    "Client rejects responses?" [shape=diamond];

    "Check Xcode running + toggle on" [shape=box];
    "Open a project in Xcode" [shape=box];
    "Use MCP_XCODE_PID or check tab targeting" [shape=box];
    "Expected: PID changes on restart" [shape=box];
    "Use XcodeMCPWrapper proxy" [shape=box];

    "Connection failed?" -> "Check Xcode running + toggle on" [label="refused/timeout"];
    "Connection failed?" -> "tools/list empty?" [label="connects OK"];
    "tools/list empty?" -> "Open a project in Xcode" [label="no tools"];
    "tools/list empty?" -> "Wrong project?" [label="tools listed"];
    "Wrong project?" -> "Use MCP_XCODE_PID or check tab targeting" [label="yes"];
    "Wrong project?" -> "Repeated permission prompts?" [label="no"];
    "Repeated permission prompts?" -> "Expected: PID changes on restart" [label="yes"];
    "Repeated permission prompts?" -> "Client rejects responses?" [label="no"];
    "Client rejects responses?" -> "Use XcodeMCPWrapper proxy" [label="strict client (Cursor)"];
}

Common Issues

| Symptom | Cause | Fix | |---------|-------|-----| | "Connection refused" | Xcode not running or MCP toggle off | Launch Xcode, enable MCP in Settings > Intelligence | | tools/list returns empty | No project open, or permission not granted | Open a project, check for permission dialog in Xcode | | Tools target wrong project | Multiple Xcode windows, wrong tab | Call XcodeListWindows, use correct tabIdentifier | | Repeated permission prompts | Client restarted (new PID) | Expected behavior — approve each time | | Cursor/strict client errors | Missing structuredContent in response | Use XcodeMCPWrapper as proxy | | "No such command: mcpbridge" | Xcode < 26.3 | Update to Xcode 26.3+ | | Slow/hanging tool calls | Large project indexing | Wait for Xcode indexing to complete |

Xcode Built-in Assistant Config

Xcode also supports MCP servers for its built-in assistants. Config files live at:

~/Library/Developer/Xcode/CodingAssistant/codex
~/Library/Developer/Xcode/CodingAssistant/ClaudeAgentConfig

These are for configuring Xcode's internal assistant, separate from external MCP client setup.

Resources

Docs: /xcode/mcp-server

Skills: axiom-xcode-mcp-tools, axiom-xcode-mcp-ref