@abluva/mcp-remote

Abluva-maintained fork of mcp-remote — a stdio proxy that connects MCP clients (Claude Desktop, Cursor, etc.) to remote MCP servers with OAuth.

Use this package when upstream mcp-remote hangs on auth, drops mid-session re-login, or refuses OAuth callbacks on localhost.

📄 Full fork changelog, upstream issue/PR mapping, and version history: ABLUVA-FORK.md

Why Abluva maintains this fork

Upstream mcp-remote is the de facto OAuth bridge for stdio-only MCP clients. Several critical OAuth bugs remain open on geelen/mcp-remote — especially mid-session token expiry, Claude Desktop hangs, and localhost callback connection refused.

@abluva/mcp-remote merges:

• jacopoc’s unmerged re-auth branch (PR #213)
• Selected open upstream PRs (#297, #290, #302, #262 partial)
• Abluva production fixes for MCP gateway OAuth (callback server lifetime, auto ports, Hub logout re-auth)

Quick start (Claude Desktop)

{
  "mcpServers": {
    "remote-example": {
      "command": "npx",
      "args": [
        "-y",
        "@abluva/mcp-remote@latest",
        "https://your-mcp-gateway.example/mcp-connect/<catalog-id>"
      ]
    }
  }
}

• -y — required for Claude (non-interactive npx install).
• Callback port — optional third argument; omitted by default (auto-selected per server URL since v0.1.40).
• After first install or upgrade: rm -rf ~/.mcp-auth then restart Claude (Cmd+Q).

What we fixed (summary)

See ABLUVA-FORK.md for the complete table and version notes.

Branches & merges

geelen/mcp-remote @ v0.1.38 (main)
        │
        ├── jacopoc/implement-reauth-after-auth-error-on-send  →  mid-session re-auth (#213)
        │
        └── abluva-research/mcp-remote (main)
                ├── v0.1.39  OAuth re-auth + eager callback server
                ├── v0.1.40  Auto callback port / EADDRINUSE recovery
                ├── v0.1.41  #297, #290, #302
                └── v0.1.42  Stale registration invalidation + port sync

Not yet included

• PR #272 — respond to initialize immediately while OAuth runs in background (Claude 60s timeout). Requires larger proxy lifecycle change; tracked for a future release.

Local build

git clone https://github.com/abluva-research/mcp-remote.git
cd mcp-remote
npm install
npm run build
node dist/proxy.js https://your-gateway.example/mcp-connect/<id>

Upstream documentation

The sections below are inherited from upstream mcp-remote (usage, headers, transport strategies, etc.). For Abluva-specific OAuth behaviour, prefer ABLUVA-FORK.md.

mcp-remote (upstream)

Connect an MCP Client that only supports local (stdio) servers to a Remote MCP Server, with auth support:

Note: this is a working proof-of-concept but should be considered experimental.

Why is this necessary?

So far, the majority of MCP servers in the wild are installed locally, using the stdio transport. This has some benefits: both the client and the server can implicitly trust each other as the user has granted them both permission to run. Adding secrets like API keys can be done using environment variables and never leave your machine. And building on npx and uvx has allowed users to avoid explicit install steps, too.

But there's a reason most software that could be moved to the web did get moved to the web: it's so much easier to find and fix bugs & iterate on new features when you can push updates to all your users with a single deploy.

With the latest MCP Authorization specification, we now have a secure way of sharing our MCP servers with the world without running code on user's laptops. Or at least, you would, if all the popular MCP clients supported it yet. Most are stdio-only, and those that do support HTTP+SSE don't yet support the OAuth flows required.

That's where mcp-remote comes in. As soon as your chosen MCP client supports remote, authorized servers, you can remove it. Until that time, drop in this one liner and dress for the MCP clients you want!

Usage

All the most popular MCP clients (Claude Desktop, Cursor & Windsurf) use the following config format:

{
  "mcpServers": {
    "remote-example": {
      "command": "npx",
      "args": [
        "@abluva/mcp-remote",
        "https://remote.mcp.server/sse"
      ]
    }
  }
}

• If npx is producing errors, consider adding -y as the first argument to auto-accept the installation of the @abluva/mcp-remote package.

      "command": "npx",
      "args": [
        "-y",
        "@abluva/mcp-remote",
        "https://remote.mcp.server/sse"
      ]

• To force npx to always check for an updated version, add the @latest flag:

      "args": [
        "-y",
        "@abluva/mcp-remote@latest",
        "https://remote.mcp.server/sse"
      ]

• To change which port @abluva/mcp-remote listens for an OAuth redirect (by default auto-selected per server URL since v0.1.40), add an additional argument after the server URL. If the port is unavailable, an open port will be chosen at random.

      "args": [
        "@abluva/mcp-remote",
        "https://remote.mcp.server/sse",
        "9696"
      ]

• To change which host @abluva/mcp-remote registers as the OAuth callback URL (by default localhost), add the --host flag.

      "args": [
        "@abluva/mcp-remote",
        "https://remote.mcp.server/sse",
        "--host",
        "127.0.0.1"
      ]

• To allow HTTP connections in trusted private networks, add the --allow-http flag. Note: This should only be used in secure private networks where traffic cannot be intercepted.

      "args": [
        "@abluva/mcp-remote",
        "http://internal-service.vpc/sse",
        "--allow-http"
      ]

• To enable detailed debugging logs, add the --debug flag. This will write verbose logs to ~/.mcp-auth/{server_hash}_debug.log with timestamps and detailed information about the auth process, connections, and token refreshing.

      "args": [
        "@abluva/mcp-remote",
        "https://remote.mcp.server/sse",
        "--debug"
      ]

• To suppress default logs, add the --silent flag. This will prevent logs from being emitted, except in the case where --debug is also passed.

      "args": [
        "@abluva/mcp-remote",
        "https://remote.mcp.server/sse",
        "--silent"
      ]

• To enable an outbound HTTP(S) proxy for mcp-remote, add the --enable-proxy flag. When enabled, mcp-remote will use the proxy settings from common environment variables (for example HTTP_PROXY, HTTPS_PROXY, and NO_PROXY).

    "args": [
      "@abluva/mcp-remote",
      "https://remote.mcp.server/sse",
      "--enable-proxy"
    ],
    "env": {
      "HTTPS_PROXY": "http://127.0.0.1:3128",
      "NO_PROXY": "localhost,127.0.0.1"
    }

• To ignore specific tools from the remote server, add the --ignore-tool flag. This will filter out tools matching the specified patterns from both tools/list responses and block tools/call requests. Supports wildcard patterns with *.

      "args": [
        "@abluva/mcp-remote",
        "https://remote.mcp.server/sse",
        "--ignore-tool",
        "delete*",
        "--ignore-tool",
        "remove*"
      ]

You can specify multiple --ignore-tool flags to ignore different patterns. Examples:

• delete* - ignores all tools starting with "delete" (e.g., deleteTask, deleteUser)
• *account - ignores all tools ending with "account" (e.g., getAccount, updateAccount)
• exactTool - ignores only the tool named exactly "exactTool"

• To change the timeout for the OAuth callback (by default 30 seconds), add the --auth-timeout flag with a value in seconds. This is useful if the authentication process on the server side takes a long time.

      "args": [
        "@abluva/mcp-remote",
        "https://remote.mcp.server/sse",
        "--auth-timeout",
        "60"
      ]

Transport Strategies

MCP Remote supports different transport strategies when connecting to an MCP server. This allows you to control whether it uses Server-Sent Events (SSE) or HTTP transport, and in what order it tries them.

Specify the transport strategy with the --transport flag:

npx @abluva/mcp-remote https://example.remote/server --transport sse-only

Available Strategies:

• http-first (default): Tries HTTP transport first, falls back to SSE if HTTP fails with a 404 error
• sse-first: Tries SSE transport first, falls back to HTTP if SSE fails with a 405 error
• http-only: Only uses HTTP transport, fails if the server doesn't support it
• sse-only: Only uses SSE transport, fails if the server doesn't support it

Static OAuth Client Metadata

MCP Remote supports providing static OAuth client metadata instead of using the mcp-remote defaults.
This is useful when connecting to OAuth servers that expect specific client/software IDs or scopes.

Provide the client metadata as a JSON string or as a @ prefixed filepath with the --static-oauth-client-metadata flag:

npx @abluva/mcp-remote https://example.remote/server --static-oauth-client-metadata '{ "scope": "space separated scopes" }'
# uses node readfile, so you probably want to use absolute paths if you're not sure what the cwd is
npx @abluva/mcp-remote https://example.remote/server --static-oauth-client-metadata '@/Users/username/Library/Application Support/Claude/oauth_client_metadata.json'

Static OAuth Client Information

Per the spec,
servers are encouraged but not required to support OAuth dynamic client registration.

For these servers, MCP Remote supports providing static OAuth client information instead.
This is useful when connecting to OAuth servers that require pre-registered clients.

Provide the client metadata as a JSON string or as a @ prefixed filepath with the --static-oauth-client-info flag:

export MCP_REMOTE_CLIENT_ID=xxx
export MCP_REMOTE_CLIENT_SECRET=yyy
npx @abluva/mcp-remote https://example.remote/server --static-oauth-client-info "{ \"client_id\": \"$MCP_REMOTE_CLIENT_ID\", \"client_secret\": \"$MCP_REMOTE_CLIENT_SECRET\" }"
# uses node readfile, so you probably want to use absolute paths if you're not sure what the cwd is
npx @abluva/mcp-remote https://example.remote/server --static-oauth-client-info '@/Users/username/Library/Application Support/Claude/oauth_client_info.json'

Claude Desktop

Official Docs

In order to add an MCP server to Claude Desktop you need to edit the configuration file located at:

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

If it does not exist yet, you may need to enable it under Settings > Developer.

Restart Claude Desktop to pick up the changes in the configuration file.
Upon restarting, you should see a hammer icon in the bottom right corner
of the input box.

Cursor

Official Docs. The configuration file is located at ~/.cursor/mcp.json.

As of version 0.48.0, Cursor supports unauthed SSE servers directly. If your MCP server is using the official MCP OAuth authorization protocol, you still need to add a "command" server and call @abluva/mcp-remote.

Windsurf

Official Docs. The configuration file is located at ~/.codeium/windsurf/mcp_config.json.

Building Remote MCP Servers

For instructions on building & deploying remote MCP servers, including acting as a valid OAuth client, see the following resources:

• https://developers.cloudflare.com/agents/guides/remote-mcp-server/

In particular, see:

• https://github.com/cloudflare/workers-oauth-provider for defining an MCP-comlpiant OAuth server in Cloudflare Workers
• https://github.com/cloudflare/agents/tree/main/examples/mcp for defining an McpAgent using the agents framework.

For more information about testing these servers, see also:

• https://developers.cloudflare.com/agents/guides/test-remote-mcp-server/

Know of more resources you'd like to share? Please add them to this Readme and send a PR!

Troubleshooting

Clear your ~/.mcp-auth directory

@abluva/mcp-remote stores all the credential information inside ~/.mcp-auth (or wherever your MCP_REMOTE_CONFIG_DIR points to). If you're having persistent issues, try running:

rm -rf ~/.mcp-auth

Then restarting your MCP client.

Check your Node version

Make sure that the version of Node you have installed is 18 or
higher. Claude
Desktop will use your system version of Node, even if you have a newer
version installed elsewhere.

Restart Claude

When modifying claude_desktop_config.json it can helpful to completely restart Claude

VPN Certs

You may run into issues if you are behind a VPN, you can try setting the NODE_EXTRA_CA_CERTS
environment variable to point to the CA certificate file. If using claude_desktop_config.json,
this might look like:

{
 "mcpServers": {
    "remote-example": {
      "command": "npx",
      "args": [
        "@abluva/mcp-remote",
        "https://remote.mcp.server/sse"
      ],
      "env": {
        "NODE_EXTRA_CA_CERTS": "{your CA certificate file path}.pem"
      }
    }
  }
}

Check the logs

• Follow Claude Desktop logs in real-time
• MacOS / Linux:
  tail -n 20 -F ~/Library/Logs/Claude/mcp*.log
• For bash on WSL:
  tail -n 20 -f "C:\Users\YourUsername\AppData\Local\Claude\Logs\mcp.log"
• Powershell:
  Get-Content "C:\Users\YourUsername\AppData\Local\Claude\Logs\mcp.log" -Wait -Tail 20

Debugging

Debug Logs

For troubleshooting complex issues, especially with token refreshing or authentication problems, use the --debug flag:

"args": [
  "@abluva/mcp-remote",
  "https://remote.mcp.server/sse",
  "--debug"
]

This creates detailed logs in ~/.mcp-auth/{server_hash}_debug.log with timestamps and complete information about every step of the connection and authentication process. When you find issues with token refreshing, laptop sleep/resume issues, or auth problems, provide these logs when seeking support.

Authentication Errors

If you encounter the following error, returned by the /callback URL:

Authentication Error
Token exchange failed: HTTP 400

You can run rm -rf ~/.mcp-auth to clear any locally stored state and tokens.

"Client" mode

Run the following on the command line (not from an MCP server):

npx -p @abluva/mcp-remote@latest mcp-remote-client https://remote.mcp.server/sse

This will run through the entire authorization flow and attempt to list the tools & resources at the remote URL. Try this after running rm -rf ~/.mcp-auth to see if stale credentials are your problem, otherwise hopefully the issue will be more obvious in these logs than those in your MCP client.