Wiring Brave Search + Filesystem MCP

“A library card and a key to your filing cabinet are two different permissions. MCP hands Claude both, one server at a time, scoped to exactly what you allow.”

Where the config lives

Claude Desktop reads its MCP servers from a JSON file. On macOS that's `~/Library/Application Support/Claude/claude_desktop_config.json`. Edit it (Claude Desktop → Settings → Developer → Edit Config opens the same file), then fully restart Claude Desktop, since it only loads servers at launch.

The two servers

Both servers run on demand via `npx`, so there's nothing to install first. The Brave server needs your Brave key in its `env`; the Filesystem server takes the directories it's allowed to touch as plain arguments.

{
  "mcpServers": {
    "brave-search": {
      "command": "npx",
      "args": ["-y", "@brave/brave-search-mcp-server", "--transport", "stdio"],
      "env": { "BRAVE_API_KEY": "YOUR_BRAVE_KEY" }
    },
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/Users/you/ObsidianVault/Briefings"
      ]
    }
  }
}

Scope: the Filesystem server can only touch what you list

The paths in the Filesystem server's `args` are the *only* directories it can read or write. Point it at your briefs subfolder, not your home directory: narrow scope is the whole safety story here. The server runs with your user's permissions, so anything you can do in that folder, it can do.

Verify it works

Restart Claude Desktop and look for the tools indicator (the servers show up as available tools). Then run a single end-to-end test in a chat:

• Ask: "Use Brave to find the 5 most significant developments in [your topic] from the last 24 hours, then write a short brief to a file called test-brief.md in my Briefings folder."
• Claude should ask to use the Brave search tool, then the filesystem write tool. Approve each.
• Check the folder: `test-brief.md` should be there, and it should open in Obsidian as a normal note.

If search fails, the Brave key or package name is the usual cause; if the write fails, the path in `args` doesn't match your real folder. Fix whichever, restart, retry. Once this round-trip works, you've validated every piece the automated build depends on. Chapter 4 just removes you from the loop.