Connect to your AI

Start the Fuse MCP server and connect it to Claude Code, Cursor, or GitHub Copilot so your agent fetches scoped context directly.

Fuse runs as a Model Context Protocol (MCP) server. Once connected, your agent gets eight tools for surveying a codebase, drilling into a type, scoping to a query or a branch, and asking one question, all returning scoped, reduced context in a single call.

Start the server

fuse serve

The server communicates over stdio: stdout carries the protocol byte stream, so all logging is routed to stderr. Every fusion runs in memory and is returned in the tool response; unlike the CLI, the server writes no files. It also keeps an on-disk analysis index warm across calls, so a multi-call task pays the analysis cost once.

Claude Code

Add a .mcp.json to your project root:

{
  "mcpServers": {
    "fuse": {
      "type": "stdio",
      "command": "fuse",
      "args": ["serve"]
    }
  }
}

Or register it in one line:

claude mcp add fuse --scope project -- fuse serve

Cursor

Add .cursor/mcp.json:

{
  "mcpServers": {
    "fuse": {
      "command": "fuse",
      "args": ["serve"]
    }
  }
}

GitHub Copilot in VS Code

Add .vscode/mcp.json:

{
  "servers": {
    "fuse": {
      "type": "stdio",
      "command": "fuse",
      "args": ["serve"]
    }
  }
}

The eight tools

Tool	Use it to
`fuse_toc`	Survey a codebase cheaply: a directory tree, symbol outline, and per-file token costs, no bodies.
`fuse_skeleton`	Get a signatures-only architecture map.
`fuse_focus`	Scope to a type, file, or path plus its dependencies and dependents.
`fuse_search`	Scope to the files a query ranks highest, plus dependencies.
`fuse_changes`	Scope to files changed since a git ref, plus dependents, with an optional review map.
`fuse_ask`	Give a task and a token budget; Fuse picks the strategy and packs to budget.
`fuse_dotnet`	Full-control .NET fusion with every option.
`fuse_generic`	Fusion for any template (Python, Go, Rust, and others).

The full parameter list for each is in the MCP tools reference, and the read-only MCP resources cover the fuse:// URI forms.

Enable the precision tier

To use the opt-in Roslyn precision tier for a server session, set the FUSE_SEMANTIC environment variable before starting fuse serve.

Learn the recommended tool sequence for a real task in Context for an agent on a large codebase.