# Mcp Claude Bridge

> Bridge an MCP stdio client (Claude Desktop) to a remote MCP server speaking the SSE transport without the need to use Node.js. Zero dependencies, single binary.

- **Type:** MCP server
- **Install:** `agentstack add mcp-lennardgeissler-mcp-claude-bridge`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [LennardGeissler](https://agentstack.voostack.com/s/lennardgeissler)
- **Installs:** 0
- **Category:** [Integrations](https://agentstack.voostack.com/c/integrations)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [LennardGeissler](https://github.com/LennardGeissler)
- **Source:** https://github.com/LennardGeissler/mcp-claude-bridge

## Install

```sh
agentstack add mcp-lennardgeissler-mcp-claude-bridge
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# mcp-claude-bridge

A tiny, dependency-free Go binary that lets **any stdio-only MCP client** (e.g. Claude Desktop) talk to a **remote MCP server** that speaks the SSE transport.

If your MCP server runs on another machine, inside a container, or behind a reverse proxy, Claude Desktop can't reach it directly — Claude only knows how to launch a local process and speak MCP over stdin/stdout. `mcp-claude-bridge` is that local process: it reads stdio frames from Claude on one side and speaks SSE + HTTP POST to the remote server on the other.

```
┌──────────────┐   stdio    ┌────────────────────┐   SSE + POST   ┌────────────┐
│ Claude       │◄──────────►│ mcp-claude-bridge  │◄──────────────►│ MCP server │
│ Desktop      │            │  (this repo)       │                │ (remote)   │
└──────────────┘            └────────────────────┘                └────────────┘
```

## Features

- **Bi-directional bridging**: stdio ↔ SSE `GET` stream + HTTP `POST` message endpoint
- **Flexible input framing**: accepts both LSP-style `Content-Length` frames and plain JSON-per-line
- **Multiple headers**: pass `--header` repeatedly for auth tokens, tenant IDs, etc.
- **Automatic reconnect** with capped exponential backoff (`--reconnect`)
- **Graceful shutdown** on `SIGINT`/`SIGTERM`
- **Zero runtime dependencies** — pure Go, single static binary
- Works on Windows, macOS, and Linux

## Quickstart

### Install

Download the latest binary for your platform from the project's GitHub Releases page, or build from source:

```bash
git clone https://github.com/LennardGeissler/mcp-claude-bridge.git
cd mcp-claude-bridge
go build -trimpath -ldflags "-s -w" -o mcp-claude-bridge ./cmd/mcp-claude-bridge
```

Go 1.22 or newer is required. On Windows, the produced file is `mcp-claude-bridge.exe`.

> **Note on `go install`**: this project deliberately uses a neutral Go module path (`mcp-claude-bridge`) so that no specific GitHub org is hardcoded into the source. As a side effect, `go install github.com/...@latest` is not supported — please `git clone` and `go build`, or use a pre-built release binary.

### Run it against a local mock

```bash
./mcp-claude-bridge --url https://your-mcp-host:5183/mcp --debug
```

Pass MCP JSON on stdin. Responses appear on stdout, one JSON document per line.

Two ready-to-pipe payloads live under [`examples/requests/`](examples/requests) for a quick smoke test:

```bash
cat examples/requests/initialize.json | ./mcp-claude-bridge --url https://your-mcp-host:5183/mcp --debug
cat examples/requests/ping.json       | ./mcp-claude-bridge --url https://your-mcp-host:5183/mcp --debug
```

### Use it from Claude Desktop

Edit your Claude Desktop config file:

| OS      | Path |
|---------|------|
| Windows | `%APPDATA%\Claude\claude_desktop_config.json` |
| macOS   | `~/Library/Application Support/Claude/claude_desktop_config.json` |
| Linux   | `~/.config/Claude/claude_desktop_config.json` |

Add an entry under `mcpServers`:

```json
{
  "mcpServers": {
    "my-remote-server": {
      "command": "C:\\Tools\\mcp-claude-bridge.exe",
      "args": [
        "--url", "https://mcp.internal:5183/mcp",
        "--header", "Authorization: Bearer s3cret",
        "--reconnect"
      ]
    }
  }
}
```

On macOS/Linux the `command` is just the absolute path to the binary. Restart Claude Desktop after editing the file.

## CLI flags

| Flag | Default | Description |
|------|---------|-------------|
| `--url` | _(required)_ | Remote MCP SSE URL, e.g. `https://host:5183/mcp` |
| `--header` | _(none)_ | Extra request header `Key: Value`. Repeatable. |
| `--post-timeout` | `15s` | Timeout for a single outbound POST |
| `--sse-header-timeout` | `15s` | Timeout for the SSE response headers on connect |
| `--reconnect` | `false` | Reconnect SSE after transport errors |
| `--reconnect-backoff` | `2s` | Initial backoff between reconnect attempts (capped at 30s, doubles on each retry) |
| `--insecure-skip-verify` | `false` | Disable TLS verification. **Do not use in production.** |
| `--debug` | `false` | Verbose logging to stderr |

Run `mcp-claude-bridge -h` to see this list at runtime.

## How input framing works

Real-world MCP clients don't all agree on a framing. The bridge accepts both common forms:

**LSP-style framed input** (used by some SDKs):

```
Content-Length: 48\r\n
\r\n
{"jsonrpc":"2.0","id":1,"method":"ping","params":{}}
```

**Plain JSON per line** (used by Claude Desktop today):

```
{"jsonrpc":"2.0","id":1,"method":"ping","params":{}}\n
```

The bridge detects which is in use per message by peeking at the first non-whitespace byte. Output on stdout is always a single JSON document followed by `\n`, which both framings handle.

## Security

- **TLS**: Always prefer proper certificates. If your remote server uses a certificate signed by an internal CA, deploy that CA to your OS trust store (Windows: *Trusted Root Certification Authorities*; macOS: *System keychain*; Linux: `/etc/ssl/certs` + `update-ca-certificates`). That is how you get working HTTPS — not by disabling verification.
- **`--insecure-skip-verify`**: skips certificate verification entirely. This makes your connection vulnerable to trivial man-in-the-middle attacks. Use it only for local development against self-signed certs on `localhost`, and never commit Claude Desktop config with this flag set for a production host.
- **Credentials in headers**: values passed via `--header` end up in the Claude Desktop config file in plaintext. Treat that file as a secret and lock down its permissions. Prefer short-lived tokens where possible.
- **Process isolation**: the bridge runs as the same user as Claude Desktop. It has no special privileges and only connects to the single URL you specify.

Vulnerability reports are welcome — see [SECURITY.md](SECURITY.md).

## Contributing

Patches, tests, and bug reports are welcome. Please read [CONTRIBUTING.md](CONTRIBUTING.md) and our [CODE_OF_CONDUCT.md](CODE_OF_CONDUCT.md) first.

## License

[MIT](LICENSE)

## Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [LennardGeissler](https://github.com/LennardGeissler)
- **Source:** [LennardGeissler/mcp-claude-bridge](https://github.com/LennardGeissler/mcp-claude-bridge)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/mcp-lennardgeissler-mcp-claude-bridge
- Seller: https://agentstack.voostack.com/s/lennardgeissler
- Browse the marketplace: https://agentstack.voostack.com/browse

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