axiom-xcode-mcp - SKILL.md Agent Skill

name: axiom-xcode-mcp description: Use when connecting to Xcode via MCP, using xcrun mcpbridge, or working with ANY Xcode MCP tool (XcodeRead, BuildProject, RunTests, RenderPreview). Covers setup, tool reference, workflow patterns, troubleshooting. license: MIT

Xcode MCP

You MUST use this skill for ANY Xcode MCP interaction — setup, tool usage, workflow patterns, or troubleshooting.

Xcode ships an MCP server (xcrun mcpbridge, available since Xcode 26.3) that exposes 20 IDE tools to external AI clients. Xcode 27 adds an explicit "Allow external agents to use Xcode tools" gate, the run-agent launch path, and an agent-extension model (custom MCP servers, skills, plug-ins). This skill suite covers setup, tool reference, workflow patterns, and troubleshooting.

When to Use

Use this skill when:

Setting up Xcode MCP for the first time
Configuring xcrun mcpbridge for any MCP client
Using any Xcode MCP tool (file ops, build, test, preview)
Building, testing, or previewing via MCP tools
Troubleshooting mcpbridge connection issues
Window/tab targeting questions
Permission dialog confusion

Routing Logic

1. Setup/Connection → xcode-mcp-setup

Triggers:

First-time Xcode MCP setup
Client-specific config (Claude Code, Cursor, Codex, VS Code, Gemini CLI)
Connection errors ("Connection refused", "No windows")
Permission dialog confusion
Multi-Xcode targeting (MCP_XCODE_PID)
Schema compliance issues with strict clients
Giving external agents access to Xcode (Intelligence settings gate)
Launching an agent via Xcode config (xcrun mcpbridge run-agent)
Exporting Xcode's skill bundles (run-agent skills export)
Extending Xcode's agent (per-agent config files, MCP servers, plug-ins)

Read: skills/xcode-mcp-setup.md

2. Using Tools & Workflows → xcode-mcp-tools

Triggers:

How to build/test/preview via MCP
Workflow patterns (BuildFix loop, TestFix loop)
Tool gotchas and anti-patterns
Window/tab targeting strategy
When to use MCP tools vs CLI (xcodebuild)
Destructive operation safety (XcodeRM, XcodeMV)

Read: skills/xcode-mcp-tools.md

3. Tool API Reference → xcode-mcp-ref

Triggers:

Specific tool parameters and schemas
Input/output format for a tool
"How does XcodeGrep work?"
"What params does BuildProject take?"
Tool category listing

Read: skills/xcode-mcp-ref.md

Decision Tree

digraph xcode_mcp_router {
    rankdir=TB;
    "User has Xcode MCP question" [shape=ellipse];
    "Setup or connection?" [shape=diamond];
    "Using tools or workflows?" [shape=diamond];
    "Need specific tool params?" [shape=diamond];

    "xcode-mcp-setup" [shape=box];
    "xcode-mcp-tools" [shape=box];
    "xcode-mcp-ref" [shape=box];

    "User has Xcode MCP question" -> "Setup or connection?";
    "Setup or connection?" -> "xcode-mcp-setup" [label="yes"];
    "Setup or connection?" -> "Using tools or workflows?" [label="no"];
    "Using tools or workflows?" -> "xcode-mcp-tools" [label="yes"];
    "Using tools or workflows?" -> "Need specific tool params?" [label="no"];
    "Need specific tool params?" -> "xcode-mcp-ref" [label="yes"];
    "Need specific tool params?" -> "xcode-mcp-tools" [label="general question"];
}

Anti-Rationalization

Thought	Reality
"I'll just use xcodebuild directly"	MCP gives IDE state, diagnostics, previews, and navigator issues that CLI doesn't expose
"I already know how to set up MCP"	Client configs differ. Permission dialog behavior is specific. Check setup skill.
"I can figure out the tool params"	Tool schemas have required fields and gotchas. Check ref skill.
"Tab identifiers are obvious"	Most tools fail silently without correct tabIdentifier. Tools skill explains targeting.
"This is just file reading, I'll use Read tool"	XcodeRead sees Xcode's project view including generated files and resolved packages

Conflict Resolution (vs Other Routers)

Domain	Owner	Why
MCP-specific interaction (mcpbridge, MCP tools, tab identifiers)	xcode-mcp	MCP protocol and tool-specific
Xcode environment (Derived Data, zombie processes, simulators)	axiom-build	Environment diagnostics, not MCP
Apple's bundled documentation (for-LLM guides/diagnostics)	apple-docs	Bundled docs, not MCP tool
`DocumentationSearch` MCP tool usage specifically	xcode-mcp	MCP tool invocation
Build failures diagnosed via CLI	axiom-build	Traditional build debugging
Build failures diagnosed via MCP tools	xcode-mcp	MCP workflow patterns

Example Invocations

User: "How do I set up Xcode MCP with Claude Code?" -> Read: skills/xcode-mcp-setup.md

User: "How do I build my project using MCP tools?" -> Read: skills/xcode-mcp-tools.md

User: "What parameters does BuildProject take?" -> Read: skills/xcode-mcp-ref.md

User: "My mcpbridge connection keeps failing" -> Read: skills/xcode-mcp-setup.md

User: "How do I target a specific Xcode window?" -> Read: skills/xcode-mcp-tools.md

User: "Can I render SwiftUI previews via MCP?" -> Read: skills/xcode-mcp-tools.md (workflow), then skills/xcode-mcp-ref.md (params)

User: "Cursor can't parse Xcode's MCP responses" -> Read: skills/xcode-mcp-setup.md (schema compliance section)

Resources

References: skills/xcode-mcp-setup.md, skills/xcode-mcp-tools.md, skills/xcode-mcp-ref.md, skills/axe-ref.md