MCP client setup

Use this page to connect Sendmux Product MCP to your AI client. Prefer hosted OAuth when your client supports it. Use local stdio or private HTTP when the client cannot complete hosted OAuth.

Replace placeholder keys and tokens before running any snippet. Do not commit smx_root_, smx_mbx_, or private HTTP bearer tokens to version control.

Choose a setup

Hosted OAuth

Use this for Claude, Cursor, Codex, Gemini CLI, Qwen Code, Kiro, OpenCode, Zed, Visual Studio, and ChatGPT.

Local stdio

Use this when your client can launch sendmux-mcp on your machine.

Private HTTP

Use this when your client needs a URL or runs outside your laptop.

Compatibility matrix

Client	Recommended setup	Works with
Claude and Claude Desktop	Hosted OAuth	Custom connector
Claude Code	Hosted OAuth	Remote HTTP, local stdio, private HTTP
Cursor	Hosted OAuth	Remote HTTP, local stdio, private HTTP
Codex	Hosted OAuth	Remote HTTP, local stdio, private HTTP
ChatGPT	Hosted OAuth app	Remote HTTPS MCP app
Gemini CLI	Hosted OAuth	Remote HTTP, local stdio, private HTTP
Qwen Code	Hosted OAuth	Remote HTTP, local stdio, private HTTP
Kiro	Hosted OAuth	Remote HTTP, local stdio, private HTTP
OpenCode	Hosted OAuth	Remote MCP, local MCP
Zed	Hosted OAuth	Remote OAuth, local command, private HTTP
Visual Studio	Hosted OAuth	Remote HTTP, local stdio
VS Code	Local stdio or private HTTP	Local stdio, private HTTP
Windsurf and Cascade	Local stdio or private HTTP	Local stdio, private HTTP
Cline	Local stdio or private HTTP	Local stdio, private HTTP
Roo Code	Local stdio or private HTTP	Local stdio, private HTTP
Warp local app	Local stdio or private HTTP	Local command, URL server
JetBrains AI Assistant	Local stdio or private HTTP	Local stdio, private HTTP
Continue	Local stdio or private HTTP	Local stdio, private HTTP
LM Studio	Private HTTP	Remote MCP using Cursor-style JSON
GitHub Copilot CLI	Local stdio or private HTTP	Local, HTTP
GitHub Copilot coding agent	Private HTTP	Repository MCP config with secrets

A client can still use Sendmux when hosted OAuth is not listed. Use local stdio if the client can launch commands, or private HTTP if it needs a URL.

Hosted OAuth clients

Use the hosted endpoint when the client supports remote MCP OAuth:

https://mcp.sendmux.ai/mcp

Claude and Claude Desktop

Custom connector with browser authorisation.

Add a custom connector with server URL https://mcp.sendmux.ai/mcp, then connect and complete the Sendmux authorisation flow.On Team and Enterprise plans, an owner may need to add the custom connector for the organisation before members can connect it.

Claude Code

Remote HTTP server with OAuth login from the client.

claude mcp add sendmux --transport http https://mcp.sendmux.ai/mcp

Use /mcp in Claude Code if the server is listed as requiring authentication.

Cursor

Remote MCP server in project or user config.

Add this to .cursor/mcp.json for one project or ~/.cursor/mcp.json for all projects.

{
  "mcpServers": {
    "sendmux": {
      "url": "https://mcp.sendmux.ai/mcp"
    }
  }
}

Cursor opens the OAuth flow when the hosted server asks for authorisation.

Codex

Remote server in trusted Codex config.

Add this to ~/.codex/config.toml or a trusted project .codex/config.toml.

[mcp_servers.sendmux]
url = "https://mcp.sendmux.ai/mcp"

Then authenticate:

codex mcp login sendmux

ChatGPT

Custom MCP app or workspace connector.

Create a custom MCP app or connector that points to https://mcp.sendmux.ai/mcp. Developer mode or workspace app setup must be available on your plan or workspace.After ChatGPT scans the tools, complete the Sendmux authorisation prompt and test the app privately before publishing it to a workspace.

Gemini CLI

Remote HTTP server in Gemini CLI settings.

Add this to your Gemini CLI settings.json.

{
  "mcpServers": {
    "sendmux": {
      "httpUrl": "https://mcp.sendmux.ai/mcp",
      "trust": false
    }
  }
}

Then run /mcp auth sendmux inside Gemini CLI.

Qwen Code

Remote HTTP server in Qwen Code settings.

Add this to .qwen/settings.json for one project or ~/.qwen/settings.json for all projects.

{
  "mcpServers": {
    "sendmux": {
      "httpUrl": "https://mcp.sendmux.ai/mcp",
      "trust": false
    }
  }
}

Use /mcp auth in Qwen Code if the server needs authentication.

Kiro

Remote MCP server in workspace or user settings.

Add this to .kiro/settings/mcp.json for one workspace or ~/.kiro/settings/mcp.json for all workspaces.

{
  "mcpServers": {
    "sendmux": {
      "url": "https://mcp.sendmux.ai/mcp",
      "disabled": false
    }
  }
}

Kiro opens the browser OAuth flow when the hosted server asks for authorisation.

OpenCode

Remote MCP server in opencode config.

Add this to opencode.json.

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "sendmux": {
      "type": "remote",
      "url": "https://mcp.sendmux.ai/mcp",
      "enabled": true
    }
  }
}

Authenticate when prompted, or run:

opencode mcp auth sendmux

Zed

Remote OAuth server in Zed settings.

Add this to Zed settings.

{
  "context_servers": {
    "sendmux": {
      "url": "https://mcp.sendmux.ai/mcp"
    }
  }
}

Do not add an Authorization header for hosted OAuth. Zed prompts for the standard MCP OAuth flow when no header is configured.

Visual Studio

Remote MCP server with editor auth prompt.

Add a remote MCP server with this JSON shape.

{
  "servers": {
    "sendmux": {
      "url": "https://mcp.sendmux.ai/mcp"
    }
  }
}

Click Auth above the server in the MCP configuration file, then complete the Sendmux authorisation flow.

Local stdio clients

Install the local package once:

pip install sendmux-mcp

Use a mailbox key for Mailbox or Sending:

export SENDMUX_MBX_KEY=smx_mbx_...

Use a root key for Management:

export SENDMUX_ROOT_KEY=smx_root_...

Claude Code

Command-launched stdio server.

claude mcp add sendmux-mailbox \
  --transport stdio \
  --env SENDMUX_API_KEY="$SENDMUX_MBX_KEY" \
  -- sendmux-mcp-mailbox

Cursor

Project or user stdio server.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "type": "stdio",
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

VS Code

Stdio server with prompted secret input.

Use an input variable so the key is not stored directly in .vscode/mcp.json.

{
  "servers": {
    "sendmux-mailbox": {
      "type": "stdio",
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "${input:sendmux-mailbox-key}"
      }
    }
  },
  "inputs": [
    {
      "type": "promptString",
      "id": "sendmux-mailbox-key",
      "description": "Sendmux mailbox API key",
      "password": true
    }
  ]
}

Codex

Stdio server with key inherited from the shell.

Run Codex with SENDMUX_API_KEY already set, then use env_vars so the value stays outside the config file.

[mcp_servers.sendmux_mailbox]
command = "sendmux-mcp-mailbox"
env_vars = ["SENDMUX_API_KEY"]

Windsurf and Cascade

Stdio server in Windsurf MCP config.

Add this to ~/.codeium/windsurf/mcp_config.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

Cline

Stdio server in Cline MCP settings.

Add this through the Cline MCP settings JSON or ~/.cline/mcp.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

Roo Code

Stdio server in Roo MCP settings.

Add this to the Roo MCP settings JSON.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      },
      "disabled": false,
      "alwaysAllow": []
    }
  }
}

Gemini CLI

Stdio server in Gemini CLI settings.

Add this to Gemini CLI settings.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "$SENDMUX_MBX_KEY"
      },
      "trust": false
    }
  }
}

Qwen Code

Stdio server in Qwen Code settings.

Add this to .qwen/settings.json or ~/.qwen/settings.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "$SENDMUX_MBX_KEY"
      },
      "trust": false
    }
  }
}

Kiro

Stdio server in workspace or user settings.

Add this to .kiro/settings/mcp.json or ~/.kiro/settings/mcp.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "args": [],
      "env": {
        "SENDMUX_API_KEY": "${SENDMUX_MBX_KEY}"
      },
      "disabled": false
    }
  }
}

OpenCode

Local MCP server in opencode config.

Add this to opencode.json.

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "sendmux-mailbox": {
      "type": "local",
      "command": ["sendmux-mcp-mailbox"],
      "environment": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      },
      "enabled": true
    }
  }
}

Zed

Local command server in Zed settings.

Add this to Zed settings.

{
  "context_servers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "args": [],
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

Warp local app

Command server in MCP server settings.

Paste this as an MCP server JSON snippet in Settings > Agents > MCP servers.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "args": [],
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

JetBrains AI Assistant

Stdio server in AI Assistant MCP settings.

Go to Settings > Tools > AI Assistant > Model Context Protocol (MCP) and add this JSON configuration over STDIO.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "args": [],
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

Continue

Stdio server YAML in the project.

Create .continue/mcpServers/sendmux-mailbox.yaml.

name: Sendmux mailbox MCP
version: 0.0.1
schema: v1
mcpServers:
  - name: Sendmux mailbox
    type: stdio
    command: sendmux-mcp-mailbox
    env:
      SENDMUX_API_KEY: smx_mbx_...

GitHub Copilot CLI

Command-launched stdio server.

copilot mcp add sendmux-mailbox \
  --env SENDMUX_API_KEY=smx_mbx_... \
  -- sendmux-mcp-mailbox

Private HTTP clients

Start a local HTTP MCP server:

SENDMUX_API_KEY=smx_mbx_... \
SENDMUX_MCP_HTTP_BEARER_TOKEN=local-mcp-token \
sendmux-mcp-mailbox --transport http --host 127.0.0.1 --port 8765

Use http://127.0.0.1:8765/mcp as the client URL.

Claude Code

HTTP transport with bearer header.

claude mcp add sendmux-local \
  --transport http \
  --header "Authorization: Bearer local-mcp-token" \
  http://127.0.0.1:8765/mcp

Cursor

HTTP server with static bearer header.

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

VS Code

HTTP server with prompted bearer token.

{
  "servers": {
    "sendmux-local": {
      "type": "http",
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer ${input:sendmux-mcp-token}"
      }
    }
  },
  "inputs": [
    {
      "type": "promptString",
      "id": "sendmux-mcp-token",
      "description": "Sendmux local MCP bearer token",
      "password": true
    }
  ]
}

Codex

Remote server with bearer token from the shell.

[mcp_servers.sendmux_local]
url = "http://127.0.0.1:8765/mcp"
bearer_token_env_var = "SENDMUX_MCP_HTTP_BEARER_TOKEN"

Windsurf and Cascade

HTTP server in Windsurf MCP config.

{
  "mcpServers": {
    "sendmux-local": {
      "serverUrl": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

Cline

HTTP server in Cline MCP settings.

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

Roo Code

Streamable HTTP server in Roo settings.

{
  "mcpServers": {
    "sendmux-local": {
      "type": "streamable-http",
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "disabled": false,
      "alwaysAllow": []
    }
  }
}

Gemini CLI

HTTP server in Gemini CLI settings.

{
  "mcpServers": {
    "sendmux-local": {
      "httpUrl": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "trust": false
    }
  }
}

Qwen Code

HTTP server in Qwen Code settings.

{
  "mcpServers": {
    "sendmux-local": {
      "httpUrl": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "trust": false
    }
  }
}

Kiro

HTTP server in workspace or user settings.

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "disabled": false
    }
  }
}

OpenCode

Remote MCP entry without OAuth.

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "sendmux-local": {
      "type": "remote",
      "url": "http://127.0.0.1:8765/mcp",
      "oauth": false,
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "enabled": true
    }
  }
}

Zed

HTTP server in Zed settings.

{
  "context_servers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

Warp local app

URL server in local agent settings.

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

Warp cloud agents should use a reachable private HTTPS endpoint, not a loopback URL on your laptop.

JetBrains AI Assistant

HTTP server in AI Assistant MCP settings.

Use the HTTP option in the MCP settings.

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

Continue

Streamable HTTP server YAML in the project.

Create .continue/mcpServers/sendmux-local.yaml.

name: Sendmux local MCP
version: 0.0.1
schema: v1
mcpServers:
  - name: Sendmux local
    type: streamable-http
    url: http://127.0.0.1:8765/mcp
    headers:
      Authorization: Bearer local-mcp-token

LM Studio

HTTP server using Cursor-style JSON.

LM Studio follows Cursor’s mcp.json notation. Open Program > Install > Edit mcp.json and add:

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

GitHub Copilot CLI

HTTP server from the Copilot CLI.

copilot mcp add --transport http \
  --header "Authorization: Bearer local-mcp-token" \
  sendmux-local http://127.0.0.1:8765/mcp

GitHub Copilot coding agent

Reachable private HTTPS endpoint for cloud agents.

Use repository-level MCP settings with a private HTTPS endpoint that the cloud agent can reach. Store the bearer token as an Agents secret or variable whose name starts with COPILOT_MCP_.

{
  "mcpServers": {
    "sendmux": {
      "type": "http",
      "url": "https://your-private-mcp.example.com/mcp",
      "headers": {
        "Authorization": "Bearer $COPILOT_MCP_SENDMUX_MCP_TOKEN"
      },
      "tools": ["*"]
    }
  }
}

GitHub Copilot coding agent does not support remote MCP servers that require OAuth. Do not point it at the hosted Sendmux OAuth endpoint.

Verify the connection

Reconnect the server

Restart or reconnect the MCP server in the client.

Check the tools

Open the client’s MCP server list or tool picker and confirm Sendmux tools appear.

Select a mailbox when needed

For a hosted multi-mailbox grant, call mailbox_list_granted_mailboxes before mailbox-specific work.

Check private HTTP auth

For private HTTP, confirm the client sends Authorization: Bearer local-mcp-token.

Next steps

MCP overview

Compare Documentation MCP, hosted Product MCP, local stdio, and private HTTP.

API keys

Create mailbox and root keys for local MCP.

Agent skills

Teach AI coding agents the Sendmux workflows and efficient defaults.

CLI

Run Sendmux workflows from your terminal.

​Choose a setup

Hosted OAuth

Local stdio

Private HTTP

​Hosted OAuth clients

​Local stdio clients

​Private HTTP clients

​Verify the connection

​Next steps

MCP overview

API keys

Agent skills

CLI

Choose a setup

Hosted OAuth clients

Local stdio clients

Private HTTP clients

Verify the connection

Next steps