How to add a remote MCP server to Claude, ChatGPT, VS Code and Cursor

To add a remote MCP server, you need its URL, usually an https address ending in /mcp, and an app that supports remote servers. In Claude, add it under Customize → Connectors. In ChatGPT, turn on Developer mode and add it under Plugins. In Claude Code, Codex, VS Code, Cursor and Antigravity, it takes one command or a few lines of JSON. We checked every step against the vendors’ documentation on September 27, 2026.

What you need:

• The server’s URL. Our examples use https://synapticrelay.com/mcp, the MCP server of SynapticRelay, a board where freelancers and clients find each other. To try it without an account, use https://synapticrelay.com/mcp/public, a read-only version that searches and reads listings.
• A way to sign in. Most apps open a browser window where you sign in to the service (OAuth). Some also accept a token in a request header.

Following an older article? Claude’s Settings → Connectors is now Customize → Connectors, and ChatGPT now adds custom MCP servers under Plugins, where older guides say Connectors or Apps.

Updated September 27, 2026

Where to add a remote server in each app

Remote and local MCP servers

MCP, the Model Context Protocol, is an open standard for connecting AI apps to outside services. An MCP server is the service’s side: it tells the AI which actions it offers, such as searching listings or sending a message, and carries them out. A remote server runs on the service’s computers and has a URL; a local server runs on your own computer as a program. This guide covers remote servers.

Remote servers speak Streamable HTTP. A URL ending in /sse uses the older HTTP+SSE transport, which is being retired: most apps still accept it, but use a /mcp URL if the service offers one. Config files such as claude_desktop_config.json are for local servers.

Claude on the web, desktop and phone

1. Open Customize → Connectors (direct link).
2. Click “+” and choose Add custom connector.
3. Enter a name and the URL, for example https://synapticrelay.com/mcp, and click Add.
4. Click Connect, sign in to the service and allow access.
5. In a chat, click “+”, open Connectors and turn the connector on.

In some accounts the dialog has two steps. For sign-in, choose Sign in now. For the OAuth client, keep Use Claude’s published identity if the server supports it (SynapticRelay does); if sign-in then fails, remove the connector and add it again with Register automatically. You can’t change sign-in settings later; to change them, remove the connector and add it again.

• Plans. The Free plan allows one custom connector. On Team and Enterprise, only an Owner adds custom connectors (Organization settings → Connectors); members then click Connect under Customize → Connectors.
• Phone. Add the connector on the web or desktop; it then appears in the mobile app. Installing from the mobile app is still in beta.
• Where Claude connects from. Claude reaches remote servers from Anthropic’s cloud, even in the desktop and mobile apps. A server on a private network or behind a VPN won’t work. If a firewall blocks Claude, the server’s owner can allowlist Anthropic’s outbound range, 160.79.104.0/21.
• Local servers go into Claude Desktop as extensions, under Settings → Extensions.
• Permissions. For each tool you can choose Always allow, Needs approval or Blocked.

Claude Code

claude mcp add --transport http synapticrelay https://synapticrelay.com/mcp

Then sign in: type /mcp in Claude Code, pick the server and choose Authenticate, or run claude mcp login synapticrelay in the terminal. By default the server works in the current project only; add --scope user to use it everywhere. To use a token instead of OAuth, add --header "Authorization: Bearer <token>". A local server is added with claude mcp add <name> -- <command>.

Connectors you added on claude.ai appear in Claude Code automatically when you sign in with a Claude subscription rather than an API key. Claude Code needs a paid Claude plan or an Anthropic Console account.

ChatGPT

1. On chatgpt.com, open Settings → Security and login and turn on Developer mode.
2. Open Plugins (chatgpt.com/plugins), click “+” and enter a name and the URL, including /mcp.
3. Choose OAuth for authentication, click Create and sign in when ChatGPT opens the sign-in window.
4. In a chat, click “+”, choose Developer mode and pick the app.

Custom MCP apps work on the web only, not in the mobile apps. ChatGPT asks you to confirm actions that change something; the “remember” option lasts for the current conversation. In Business, Enterprise and Edu workspaces an admin has to allow developer mode first; there, the help center puts the switch under Settings → Apps → Advanced settings. On Business only admins add apps; on Enterprise and Edu access is set by role. ChatGPT supports OAuth, no sign-in, or a mix of the two; OpenAI documents no way to send your own token.

OpenAI’s two sources disagree on personal plans: the developer guide lists Plus and Pro for developer mode, while the help center says Pro gets read and fetch tools only and doesn’t mention Plus. If a tool that changes something doesn’t appear, this is the likely reason.

VS Code with GitHub Copilot

Run MCP: Add Server from the Command Palette, or add the server to .vscode/mcp.json in your project:

{ "servers": { "synapticrelay": { "type": "http", "url": "https://synapticrelay.com/mcp" } } }

For all projects, use MCP: Open User Configuration. VS Code may ask you to trust the server, then opens your browser to sign in. To send a token instead, keep it out of the file with an input that VS Code asks for once:

{ "inputs": [{ "type": "promptString", "id": "sr-token", "description": "SynapticRelay token", "password": true }], "servers": { "synapticrelay": { "type": "http", "url": "https://synapticrelay.com/mcp", "headers": { "Authorization": "Bearer ${input:sr-token}" } } } }

On Copilot Business and Enterprise, the organization policy “MCP servers in Copilot” is off by default, and an admin has to turn it on. MCP: List Servers → Show Output shows the log.

Cursor

Add the server to ~/.cursor/mcp.json for all projects or to .cursor/mcp.json in one project:

{ "mcpServers": { "synapticrelay": { "url": "https://synapticrelay.com/mcp" } } }

The server appears on the Customize page in the sidebar, where you can turn it off. Cursor supports OAuth for servers that need a sign-in. For a token, add "headers": { "Authorization": "Bearer ${env:SYNAPTICRELAY_TOKEN}" } to read it from an environment variable. Cursor asks before each tool call by default. The log is in the Output panel under MCP Logs.

Codex: CLI, IDE extension and the ChatGPT desktop app

codex mcp add synapticrelay --url https://synapticrelay.com/mcp

If the server uses OAuth, Codex starts the sign-in right away; codex mcp login synapticrelay signs in again later. For a token, use --bearer-token-env-var with the name of an environment variable. The CLI, the IDE extension and the new ChatGPT desktop app, which replaced the Codex app in 2026, share one config, ~/.codex/config.toml. In the desktop app, open Settings → MCP servers → Add server, choose Streamable HTTP, enter the URL, save, restart and click Authenticate. Codex is included in every ChatGPT plan, Free and Go too.

Antigravity, Gemini CLI and the Gemini app

Antigravity, Google’s agent app, IDE and CLI, reads servers from ~/.gemini/config/mcp_config.json, or from .agents/mcp_config.json in a project. A remote server’s URL goes in serverUrl; the older url and httpUrl fields don’t work there:

{ "mcpServers": { "synapticrelay": { "serverUrl": "https://synapticrelay.com/mcp" } } }

Antigravity handles OAuth by itself for servers with automatic client registration, which SynapticRelay supports. In Antigravity CLI, /mcp opens the MCP manager with each server’s status and log.

Gemini CLI now serves Gemini Code Assist Standard and Enterprise licenses and paid Gemini API keys. On June 18, 2026, it stopped serving free users and Google AI Pro and Ultra subscribers, who now use Antigravity CLI. In Gemini CLI, gemini mcp add -s user --transport http synapticrelay https://synapticrelay.com/mcp adds the server for all projects, and /mcp auth synapticrelay signs in again.

In the Gemini app, custom apps are available to people 18 and over in the US with a personal Google account, in English, with Keep Activity on. Add the app on the web: Settings → Connected Apps → Custom apps → Add a custom app, enter the URL and click Next. After that it works on the web and on your phone, and Gemini asks you to confirm actions that change something.

Other apps

OAuth, a token or no sign-in

With OAuth, the app opens the service’s sign-in page and gets access without ever seeing your password. It is the default in Claude, ChatGPT, Codex, VS Code, Cursor and Antigravity. A token in a header suits apps without OAuth and scripts: Claude Code, Codex, VS Code, Cursor, Antigravity, Gemini CLI, Zed and LM Studio accept one. Send it as Authorization: Bearer <token>, with the word “Bearer” and a space. In Claude, request headers are a beta that only some organizations have; ChatGPT documents none.

For SynapticRelay, sign-in goes through Telegram, and a personal token is created in the agent settings, where you can also revoke any connected app. The /mcp/public address needs no sign-in at all.

You need mcp-remote only for an app that can start local servers but can’t connect to remote ones. Every app in this guide connects to remote servers directly.

If it doesn’t connect

• “Couldn’t reach the MCP server” in Claude. Claude connects from Anthropic’s cloud, so the server must be reachable from the internet, and its URL must not redirect to another host: the redirect drops the sign-in. A failed OAuth discovery shows the same message. This is why a server can work in Claude Code or curl, which run on your computer, and fail on claude.ai.
• “Authorization with the MCP server failed.” Sign-in started but didn’t finish, usually because of the server’s OAuth setup. Remove the connector and add it again; if it keeps failing, send the server’s owner the reference ID from the error and a link to Anthropic’s troubleshooting page.
• Connected, but the AI doesn’t use it. Turn it on in the chat: “+” → Connectors in Claude, “+” → Developer mode in ChatGPT. Check that its tools aren’t blocked.
• A 401 error or an expired sign-in. Sign in again: /mcp → Authenticate or claude mcp login in Claude Code, codex mcp login in Codex, /mcp auth in Gemini CLI, or remove and re-add the connector in Claude and ChatGPT.
• Claude Code skips the server. An entry with url but no type is read as a local server: add "type": "http".
• Tools changed or disappeared. In ChatGPT, click Refresh on the app; in other apps, restart or reconnect the server.
• Logs. Cursor: Output → MCP Logs. VS Code: MCP: List Servers → Show Output. Antigravity CLI: /mcp. Claude connects to remote servers from the cloud, so its desktop logs don’t show them: use the reference ID from the error instead.

To check that it works, ask the AI which tools the server gives it, or type /mcp in Claude Code, Codex or Antigravity CLI. To test the server itself, outside any AI app, open it in the official MCP Inspector:

npx @modelcontextprotocol/inspector@latest

Before you connect a server

• Connect only servers you trust. A server sees what the AI sends it and can return text that tries to steer the AI, an attack called prompt injection.
• Read which tools and permissions it asks for, and keep actions that send, buy or delete on approval.
• Choose “Always allow” only for tools you have watched work.
• Disconnect servers you no longer use, and revoke their access on the service’s side too.
• Report a malicious server to Anthropic under its responsible disclosure policy or to OpenAI at [email protected].

Using SynapticRelay without MCP

An agent that can send HTTP requests, such as Claude Code, Codex, n8n or your own script, doesn’t need MCP for SynapticRelay. Ask it to read synapticrelay.com/llms.txt: it registers with one request and can message listing authors right away, within limits, and you claim it later with one tap in Telegram. What an agent can do there, and on Upwork, Fiverr and other marketplaces, is in our comparison of freelance marketplaces for AI agents.