perfonext-build-mcp

perfonext-build-mcp is an MCP server for loading and analyzing Next.js build artifacts. It gives GitHub Copilot and other MCP clients structured bundle and route-size data they can reason over instead of forcing the model to inspect raw .next manifests.

What It Does

• loads Next.js build artifacts from a .next directory
• ranks the largest user-facing routes by emitted bundle footprint
• identifies the heaviest shared chunks that affect multiple routes
• keeps loaded build snapshots in memory so an MCP client can inspect them without re-reading the same build

Inputs

The MVP reads build artifacts developers already have after running next build:

• .next/build-manifest.json
• .next/prerender-manifest.json when present
• .next/app-build-manifest.json when present
• optional captured next build output text to derive build duration

Tools

| Tool | Description | |------|-------------| | load_build_stats | Parse a Next.js .next directory and load the build snapshot into memory | | get_largest_routes | Rank the heaviest user-facing routes by total emitted chunk bytes | | get_shared_chunks | Rank shared chunks by size and show which routes depend on them | | compare_builds | Compare a baseline and current build snapshot to show which routes and chunks grew or shrank |

The output stays machine-readable and includes raw byte counts so Copilot can explain regressions, prioritise fixes, and suggest concrete dependency or import-level follow-up.

Install

Run directly with npx:

npx -y @perfonext/build-mcp

Or install globally:

npm install -g @perfonext/build-mcp

The executable command remains perfonext-build-mcp after installation.

MCP Configuration

Add this server to VS Code settings:

{
  "mcp": {
    "servers": {
      "perfonext-build": {
        "command": "npx",
        "args": ["-y", "@perfonext/build-mcp"]
      }
    }
  }
}

Example Copilot Prompts

• "Load the Next.js build in ./.next and show me the largest routes."
• "Which shared chunks are affecting the most routes in this build?"
• "Summarize the build footprint and tell me which routes ship the most JavaScript."
• "Compare my baseline and current .next builds and show me which routes or shared chunks grew the most."

Development

npm install
npm run build
npm test

Sample fixtures for local validation live under tests/fixtures/.

License

MIT