Installation - SenderKit

This page covers all supported ways to connect to SenderKit’s MCP server: OAuth (for clients that handle auth themselves), the hosted API-key endpoint, and the local stdio server bundled in the CLI.

Connect via OAuth

If your client handles auth through OAuth rather than a manual API key (Claude on the web, desktop, or mobile; ChatGPT custom connectors; or any other OAuth-compatible MCP client), you don’t need an API key — the client drives the auth flow through SenderKit’s OAuth 2.1 authorization server.

Find the custom connector / MCP section in your client

In Claude, this is typically Customise → Add custom connector. Other clients have similar settings screens.

Add `https://mcp.senderkit.com` as the server URL

The client will discover SenderKit’s OAuth endpoints automatically.

You’ll be redirected to senderkit.com to authenticate.

Choose a workspace and mode on the consent screen

Pick which workspace the agent should act on, and whether it should use live mode (real delivery) or test mode (recorded but not sent). You can revoke the connection at any time from Dashboard → Settings → Connected Apps.

The workspace and mode you choose at consent time are fixed for that connection. To switch, revoke and reconnect. Call senderkit_context from within a session to confirm which workspace and mode are active.

Prerequisites (API-key connection)

A SenderKit API key. Create one in the dashboard; see Authentication. The same key prefix (sk_live_ / sk_test_) controls live vs test mode.
For local stdio mode: @senderkit/cli installed and on your PATH.

Hosted or local?

	Hosted	Local stdio
Endpoint	`https://mcp.senderkit.com`	`senderkit mcp` subprocess
Auth	`Authorization: Bearer <key>` header	`SENDERKIT_API_KEY` env var
Network hop	yes	none
Requires Node.js	no	yes (via the CLI)

The tools and behavior are identical. Pick whichever fits your setup.

Auto-install with the CLI

If you have the CLI installed, senderkit mcp install writes the config for you. By default it configures the hosted endpoint with OAuth — no API key is stored; your client handles sign-in. Pass --client <name> to target a single client instead of every detected one.

# Hosted OAuth config for every detected client (default — no API key stored)
senderkit mcp install

# Hosted with API key bearer auth instead of OAuth
senderkit mcp install --api-key-auth

# Local stdio subprocess config
senderkit mcp install --local

# Target one client
senderkit mcp install --client cursor

# Print the config to stdout instead of writing
senderkit mcp install --client claude-desktop --print

Supported --client values: claude-code, claude-desktop, cursor, windsurf, vscode, zed, codex, opencode, or all (the default).

Manual configuration

If you’d rather edit configuration files by hand, the tabs below show the exact block per client.

Use claude mcp add — it writes to ~/.claude.json under projects.<cwd>.mcpServers.senderkit (local scope) or the top-level mcpServers.senderkit (user scope).

claude mcp add --transport http --scope user senderkit \
  https://mcp.senderkit.com \
  --header "Authorization: Bearer $SENDERKIT_API_KEY"

claude mcp add --scope user \
  --env SENDERKIT_API_KEY=$SENDERKIT_API_KEY \
  senderkit -- senderkit mcp

Verify with claude mcp list, or /mcp from inside a Claude Code session.

Edit claude_desktop_config.json. Open it via Claude → Settings → Developer → Edit Config.Location:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json

Claude Desktop only speaks stdio, so the hosted variant bridges through mcp-remote.

{
  "mcpServers": {
    "senderkit": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://mcp.senderkit.com",
        "--header",
        "Authorization: Bearer ${SENDERKIT_API_KEY}"
      ]
    }
  }
}

{
  "mcpServers": {
    "senderkit": {
      "command": "senderkit",
      "args": ["mcp"],
      "env": { "SENDERKIT_API_KEY": "sk_test_…" }
    }
  }
}

Fully quit Claude Desktop and reopen it for the change to take effect — closing the window isn’t enough.

Edit ~/.cursor/mcp.json.

{
  "mcpServers": {
    "senderkit": {
      "url": "https://mcp.senderkit.com",
      "headers": {
        "Authorization": "Bearer ${SENDERKIT_API_KEY}"
      }
    }
  }
}

{
  "mcpServers": {
    "senderkit": {
      "command": "senderkit",
      "args": ["mcp"],
      "env": { "SENDERKIT_API_KEY": "sk_test_…" }
    }
  }
}

Edit ~/.codeium/windsurf/mcp_config.json. Windsurf’s native remote MCP support is uneven, so the hosted variant bridges through mcp-remote.

{
  "mcpServers": {
    "senderkit": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://mcp.senderkit.com",
        "--header",
        "Authorization: Bearer ${SENDERKIT_API_KEY}"
      ]
    }
  }
}

{
  "mcpServers": {
    "senderkit": {
      "command": "senderkit",
      "args": ["mcp"],
      "env": { "SENDERKIT_API_KEY": "sk_test_…" }
    }
  }
}

Edit mcp.json in your VS Code user directory.Location:

macOS: ~/Library/Application Support/Code/User/mcp.json
Windows: %APPDATA%\Code\User\mcp.json
Linux: ~/.config/Code/User/mcp.json

VS Code uses the top-level key servers (not mcpServers) and requires a type field.

{
  "servers": {
    "senderkit": {
      "type": "http",
      "url": "https://mcp.senderkit.com",
      "headers": {
        "Authorization": "Bearer ${SENDERKIT_API_KEY}"
      }
    }
  }
}

{
  "servers": {
    "senderkit": {
      "type": "stdio",
      "command": "senderkit",
      "args": ["mcp"],
      "env": { "SENDERKIT_API_KEY": "sk_test_…" }
    }
  }
}

Edit ~/.config/zed/settings.json — Zed calls them context_servers.

{
  "context_servers": {
    "senderkit": {
      "url": "https://mcp.senderkit.com",
      "headers": {
        "Authorization": "Bearer ${SENDERKIT_API_KEY}"
      }
    }
  }
}

{
  "context_servers": {
    "senderkit": {
      "command": "senderkit",
      "args": ["mcp"],
      "env": { "SENDERKIT_API_KEY": "sk_test_…" }
    }
  }
}

Edit ~/.codex/config.toml. Codex has native streamable-HTTP MCP support with OAuth — sign in with codex mcp login senderkit after writing the config.

[mcp_servers.senderkit]
url = "https://mcp.senderkit.com"

[mcp_servers.senderkit]
url = "https://mcp.senderkit.com"
bearer_token_env_var = "SENDERKIT_API_KEY"

[mcp_servers.senderkit]
command = "senderkit"
args = ["mcp"]

[mcp_servers.senderkit.env]
SENDERKIT_API_KEY = "sk_test_…"

Edit ~/.config/opencode/opencode.json.

{
  "mcp": {
    "senderkit": {
      "type": "remote",
      "url": "https://mcp.senderkit.com",
      "enabled": true,
      "headers": {
        "Authorization": "Bearer ${SENDERKIT_API_KEY}"
      }
    }
  }
}

{
  "mcp": {
    "senderkit": {
      "type": "local",
      "command": ["senderkit", "mcp"],
      "enabled": true,
      "environment": { "SENDERKIT_API_KEY": "sk_test_…" }
    }
  }
}

Self-hosting the HTTP server

If you’d rather not rely on the hosted endpoint, the CLI exposes the same server over Streamable HTTP. Point your client at it the same way you’d point at the hosted URL.

# Listens on http://localhost:3000/mcp
senderkit mcp --http --port 3000

Each request still needs Authorization: Bearer <key>. The server is stateless: every request authenticates independently, so a single process can serve multiple users or workspaces.

Troubleshooting

The server doesn't appear in my client.

Most clients only load MCP servers at startup. Fully quit and restart the client after editing config. For Claude Code, run /mcp to see the live list; for Claude Desktop, restart from the menu rather than just closing the window.

The client reports an authentication failure.

For OAuth clients (Claude web/desktop/mobile, etc.): the connection may have been revoked. Go to Dashboard → Settings → Connected Apps, revoke the entry for your client, and reconnect.For hosted (API key), check that the Authorization header value is exactly Bearer sk_live_… or Bearer sk_test_… — no extra whitespace, no missing Bearer prefix. The server returns 401 for any missing or unrecognized key. Revoked keys also return 401; create a new key in the dashboard.For local stdio, the server reads SENDERKIT_API_KEY from the environment passed to the subprocess (the env block in your client config, or your shell if you launch the client from a terminal). If the key isn’t set, senderkit mcp exits at startup with No SenderKit API key found.

`senderkit: command not found` or `spawn senderkit ENOENT`.

The local stdio config calls the senderkit binary directly. Install the CLI globally (npm install -g @senderkit/cli) and confirm it’s on your PATH with which senderkit. If your client launches outside your shell’s PATH (Claude Desktop on macOS often does), use the absolute path in the command field — e.g. /usr/local/bin/senderkit — or switch to the hosted variant.

Hosted setup fails through `mcp-remote`.

mcp-remote requires Node.js 18+. Confirm with node --version. If npx is missing entirely, install Node from nodejs.org, or switch to a client with native remote MCP support (Claude Code, Cursor, VS Code, Zed, Codex, opencode).

The agent can see tools but every call returns an error.

Look at the tool’s error text — the server returns structured messages for invalid input (invalid_request: …), missing templates (template_not_found: …), rate limits (rate_limited: …), and 401s. The shape matches the REST API, so anything in the API troubleshooting guide applies.

Quickstart

The fastest path: Claude Code, hosted, in five minutes.

Tools

The full surface, parameter by parameter.

​Connect via OAuth

​Prerequisites (API-key connection)

​Hosted or local?

​Auto-install with the CLI

​Manual configuration

​Self-hosting the HTTP server

​Troubleshooting

Quickstart

Tools

Connect via OAuth

Prerequisites (API-key connection)

Hosted or local?

Auto-install with the CLI

Manual configuration

Self-hosting the HTTP server

Troubleshooting