How do I add Immiscible’s MCP server to Claude Code, Cursor or VS Code?

The MCP server is at https://immiscible.fly.dev/mcp (Streamable HTTP), and it takes an agent key as a bearer token or an OAuth sign-in. In Claude Code it is one command, claude mcp add --transport http immiscible https://immiscible.fly.dev/mcp --header "Authorization: Bearer $IMMISCIBLE_AGENT_KEY"; in other clients it is one JSON entry, below.

#1. Get an agent key

npx immiscible init --yes

This writes IMMISCIBLE_URL and IMMISCIBLE_AGENT_KEY to .env (and adds .env to .gitignore). An AI coding agent can run it too: see can an AI coding agent install it itself?. Load the key into your shell with export $(grep IMMISCIBLE_ .env | xargs), or skip the key and sign in with OAuth where the client supports it.

#2. Add the server to your client

npx immiscible mcp                    # every client's setup, for your server
npx immiscible mcp --client cursor    # one client; --json for a script

It prints the entries below for your own server address, and changes nothing.

claude mcp add --transport http immiscible https://immiscible.fly.dev/mcp \
  --header "Authorization: Bearer $IMMISCIBLE_AGENT_KEY"

{
  "mcpServers": {
    "immiscible": {
      "type": "http",
      "url": "https://immiscible.fly.dev/mcp",
      "headers": { "Authorization": "Bearer ${IMMISCIBLE_AGENT_KEY}" }
    }
  }
}

{
  "mcpServers": {
    "immiscible": {
      "url": "https://immiscible.fly.dev/mcp",
      "headers": { "Authorization": "Bearer ${env:IMMISCIBLE_AGENT_KEY}" }
    }
  }
}

{
  "inputs": [
    { "type": "promptString", "id": "immiscible-agent-key", "description": "Immiscible agent key (ask_...)", "password": true }
  ],
  "servers": {
    "immiscible": {
      "type": "http",
      "url": "https://immiscible.fly.dev/mcp",
      "headers": { "Authorization": "Bearer ${input:immiscible-agent-key}" }
    }
  }
}

{
  "mcpServers": {
    "immiscible": {
      "serverUrl": "https://immiscible.fly.dev/mcp",
      "headers": { "Authorization": "Bearer ${env:IMMISCIBLE_AGENT_KEY}" }
    }
  }
}

[mcp_servers.immiscible]
url = "https://immiscible.fly.dev/mcp"
bearer_token_env_var = "IMMISCIBLE_AGENT_KEY"

• Claude Code: the command stores the header for you. .mcp.json in a shared project expands ${IMMISCIBLE_AGENT_KEY} from each person’s environment, and Claude Code asks each person to approve the server once.
• Cursor: .cursor/mcp.json in the project, or ~/.cursor/mcp.json for every project. npx immiscible mcp --client cursor also prints a one-click install link.
• VS Code (GitHub Copilot agent mode): code --add-mcp '{"name":"immiscible","type":"http","url":"https://immiscible.fly.dev/mcp"}' adds it with OAuth sign-in instead of a key; npx immiscible mcp --client vscode also prints a vscode:mcp/install link.
• Windsurf (now Devin Desktop): ~/.config/devin/mcp_config.json (on Windows %APPDATA%\devin\mcp_config.json; older Windsurf releases read ~/.codeium/windsurf/mcp_config.json).
• Codex CLI: codex mcp add immiscible --url https://immiscible.fly.dev/mcp --bearer-token-env-var IMMISCIBLE_AGENT_KEY writes the entry above.
• Gemini CLI: gemini mcp add --transport http -H "Authorization: Bearer $IMMISCIBLE_AGENT_KEY" immiscible https://immiscible.fly.dev/mcp, or the Gemini extension in packages/immiscible-gemini.
• Claude Code plugin and Claude Desktop: see install in your assistant for the plugin (hook, MCP server, skill and analyst) and the .mcpb bundle.
• Claude, ChatGPT and other connector clients: add https://immiscible.fly.dev/mcp as a custom connector and sign in. You choose which agent the connection acts as on the consent screen. See connectors.

#3. Check it works

claude mcp list        # Claude Code: immiscible should show as connected
npx immiscible doctor  # the server, the clock, the key and the hook

The client should list eleven tools: request_payment, request_personal_data, authorize_action, check_action_status, explain_decision and settle_action, and the AI spend analyst’s spend_summary, find_waste, unwatched_keys, set_budget and revoke_key. What each is for is in the MCP server.

#Can an AI coding agent install it itself?

Yes, with a person allowing the sign-in once. Every command runs without a terminal: input comes from flags, --json prints one object, and each outcome has its own exit code.

npx immiscible login --json        # line 1: a link for the person to open; line 2, once they allow it: the result
npx immiscible init --yes --json   # creates the agent and its rule, writes .env, installs the Claude Code hook, tests the gate
npx immiscible mcp --client claude-code --json
npx immiscible doctor --json       # exit 0 when nothing failed

The agent should show the person the verification_uri_complete from the first line and wait; nothing is allowed until a person signs in and approves in the browser. In CI, use a token instead: IMMISCIBLE_TOKEN from immiscible token create --name ci. Exit code 3 means not signed in, 4 means a flag is needed (the error names it), and 10 means the agent’s rule waits for another owner to confirm.

#Is the MCP server enough on its own?

No. Through the MCP server the model asks before it acts, and a model can choose not to ask. For Claude Code, add the hook, which Claude Code runs before every tool call whatever the model decides (npx immiscible init installs it). For other tools, put them behind the MCP proxy, which holds their credentials so the agent has no other way in.

#Which clients has this been tested with?

The server, the Claude Code command, .mcp.json and the Claude Code plugin are tested against Claude Code 2.1, the Gemini extension with gemini extensions validate, and the Desktop bundle with the MCPB tools. Cursor’s agent reads the Cursor entry (running it needs a Cursor account). The Codex, VS Code and Windsurf entries follow each client’s documentation as of October 2026 and are not yet tested; if a client changes its format, npx immiscible mcp is where we fix it.