Windsurf MCP: Add a Custom Server to Cascade
Windsurf adds MCP servers to Cascade from a plugin store, with a custom entry for anything not in it. The store covers the popular servers in a click. Everything else goes through one JSON file, and knowing where that file lives saves the usual hunt through settings.
Adding a server
Open Settings → Tools → Windsurf Settings, find the MCP Servers section, and click Add Server. From there either pick one of the pre-populated popular servers, or choose Add custom server + to write your own entry.
The alternative route to the same place: the Windsurf - Settings button in the bottom right corner, then Advanced → Cascade, then the MCP Servers section.
Configuration is stored at:
~/.codeium/windsurf/mcp_config.jsonThat file lists every server Cascade can connect to. Editing it directly works and is often quicker than the UI once you know the shape you want. If you are adding a server from the plugin store and it offers a default configuration, leaving the Server Config field empty tells Windsurf to use the store’s default rather than nothing.
When a server does not appear in Cascade
Two causes account for most of it. Either the JSON is malformed, in which case Cascade skips the entry silently rather than complaining, or the server is failing to start and the store entry looks fine because the config is fine. Reload Windsurf after editing the file; Cascade reads it at startup rather than watching it.
As with every editor agent, more servers is not strictly better. Each one adds tools the model has to choose between, and a long list makes tool selection worse rather than the agent more capable.
What the protocol does not give you
There is no such thing as an MCP trigger. The protocol's own working group says plainly that clients learn about server-side changes by polling for them, and a real event mechanism remains unshipped. Carly is where that part lives, watching thousands of apps and starting the work itself.
This is the honest ceiling on every MCP client, Windsurf included. Cascade calls a server when it needs something during your session. Nothing on the other side is being watched, so a message landing in your inbox or a record changing in your CRM produces no reaction at all until you ask about it.
Give Cascade one server that reaches your whole working life
Carly is a remote MCP server holding your mail, calendars, files, and business tools behind a single endpoint, with workflows that start on real events rather than on a prompt.
- Add your accounts to Carly. Sign in at carlyassistant.com, open Integrations, pick the service, click Connect, and authorize. Click Connect again for the next one and keep going for as many as you want. Carly connects to thousands of apps.
- Add Carly to Windsurf. Open Settings → Tools → Windsurf Settings → Add Server → Add custom server +, or add this to
~/.codeium/windsurf/mcp_config.json:
{
"mcpServers": {
"carly": {
"serverUrl": "https://carlyassistant.com/mcp/"
}
}
}- Reload Windsurf and Cascade can check your calendar, pull the thread describing a bug, or file an outcome without you leaving the editor.
Free Zapier-style workflows; AI agents from $35/month. Connecting Carly costs nothing.
Frequently Asked Questions
How do I add an MCP server to Windsurf?
Settings → Tools → Windsurf Settings → MCP Servers → Add Server, then either choose a popular server or select “Add custom server +” to enter your own.
Where is Windsurf’s MCP config file?
~/.codeium/windsurf/mcp_config.json. It lists every server Cascade can connect to, and editing it directly works.
Why isn’t my MCP server showing up in Cascade?
Usually malformed JSON, which Cascade skips without an error, or a server that fails to start. Reload Windsurf after editing, since the file is read at startup.
Can a Windsurf MCP server run something on a schedule?
No. MCP has no scheduler or event mechanism, so servers respond only when Cascade calls them.
More: Cursor MCP · Claude Code MCP · How to install an MCP server in 7 AI clients · MCP servers: the complete list · What is MCP?
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