---

name: mcp-source description: Switch MCP for Unity package source in connected Unity projects. Use /mcp-source [main|beta|branch|local] to swap between upstream releases, your remote branch, or local dev checkout.

Switch MCP for Unity Package Source

You are switching the com.coplaydev.unity-mcp package source in one or more Unity projects.

allowed-tools

Bash, Read, Edit, ReadMcpResourceTool, ListMcpResourcesTool

Instructions

1. Parse arguments

The user's argument is: $ARGUMENTS

Valid values: main, beta, branch, local, or empty.

If empty or not one of the four valid values, ask the user to choose:

• main — upstream main branch (stable releases)
• beta — upstream beta branch (pre-release)
• branch — your current remote branch (for testing a PR)
• local — local file reference to your checkout (for live dev iteration)

2. Detect repo context

Run these git commands from the current working directory to find the unity-mcp repo:

git rev-parse --show-toplevel    # → repo_root
git rev-parse --abbrev-ref HEAD  # → branch_name
git remote get-url origin        # → origin_url

Convert SSH origins to HTTPS: if origin_url starts with git@github.com:, transform it to https://github.com/{owner}/{repo}.git.

3. Discover target Unity projects

Try two approaches to find Packages/manifest.json files to update:

Approach A — MCP resources (preferred): Read mcpforunity://project/info for each connected Unity instance (use ListMcpResourcesTool to find available instances). Extract projectRoot and use {projectRoot}/Packages/manifest.json.

Approach B — filesystem fallback: If no MCP instances are connected, search upward from the current working directory for Packages/manifest.json files using Bash:

find "$(pwd)" -maxdepth 3 -name "manifest.json" -path "*/Packages/manifest.json" 2>/dev/null

If multiple manifests are found, update all of them (confirming with the user first).

4. Build the package URL

Based on the user's selection, construct the dependency value:

Selection	URL
main	https://github.com/CoplayDev/unity-mcp.git?path=/MCPForUnity#main
beta	https://github.com/CoplayDev/unity-mcp.git?path=/MCPForUnity#beta
branch	{origin_https}?path=/MCPForUnity#{branch_name}
local	file:{repo_root}/MCPForUnity

For branch: use the HTTPS-normalized origin URL and current git branch name. For local: use the absolute path to the repo root with file: prefix (no //), e.g. file:/Users/davidsarno/unity-mcp/MCPForUnity.

5. Update each manifest

For each discovered manifest.json:

1. Read the file with the Read tool
2. Find the "com.coplaydev.unity-mcp" dependency line
3. Use the Edit tool to replace the old value with the new URL
4. Report what was changed: old value → new value, file path

6. Report results

After updating, tell the user:

• Which manifests were updated
• The old and new package source values
• Remind them: "Unity will re-resolve the package automatically. If it doesn't, open Package Manager and click Refresh."