Duct's agent can use any MCP server you connect. Six are one click away (OpenSEO, PostHog, Notion, Linear, Railway and Cloudflare), and any other public server connects by its address.
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How to connect a server
In the Duct app, open Connections. The ready-made servers are listed there, and any other connects by its address.
Choose OpenSEO, PostHog, Notion, Linear, Railway or Cloudflare. For anything else, paste the server's https address.
One click where the server supports sign-in. Where it does not, paste an API key from the vendor. Duct keeps it encrypted.
Then ask in the chat. The agent looks through the tools on the servers you connected, calls the one that fits, and answers from what comes back.
Ready-made
Pick one on Connections and sign in with the account you already have. Each address is here for reference; you never have to type it.
Keyword volume, difficulty and backlinks.
https://app.openseo.so/mcpTry: Which keywords on this list are worth the effort to rank for?
The pages and databases in your workspace.
https://mcp.notion.com/mcpTry: What did we decide in the launch plan?
Your issues and projects.
https://mcp.linear.app/mcpTry: Which issues in the onboarding project are still open?
Your product analytics.
https://mcp.posthog.com/mcpTry: Which onboarding step loses the most people?
Your services, deployments, logs and variables.
https://mcp.railway.comTry: Did yesterday's deploy go out cleanly?
Your account through its API: Workers, DNS and analytics.
https://mcp.cloudflare.com/mcpTry: How much of last week's traffic was bots?
Any other server
Duct connects to any MCP server it can reach over the public internet. Here is what that takes, and what does not work.
https:// address serving MCP over Streamable HTTP.What the agent will and won't do
The same rules hold for every server you connect, with one difference: a server you add by its address asks before every call.
When OpenSEO, PostHog, Notion or Linear marks a tool read-only, the agent calls it without stopping to ask. Railway and Cloudflare get no such trust, because their reads can return your secrets, and nor does a server you add by address: every call to those asks first.
Any other call pauses and shows you everything it will send. Approve it or skip it.
What a server sends back is treated as data to read, never as instructions to follow.
Sign-ins and API keys stay on Duct's side, encrypted, and are never shown to the model.
A server belongs to the person who connected it, and only their own chats use it, in any project. Someone you share a project with connects their own and never reads through yours.
Today, connected servers are used in the insights chat. Scheduled briefs and Content Studio do not call them yet.
Troubleshooting
The server offers no sign-in Duct can use. Create an API key in the vendor's settings and paste it on Connections.
The sign-in expired, or was revoked on the vendor's side. Press Reconnect on Connections and sign in again.
The address points at your own computer or a private network. The hosted service only calls public internet addresses, so a local or internal server cannot be reached.
Both only admit clients they have approved in advance, so their server address alone is not enough. They do not work with Duct yet.
Some do, on the vendor's side. A call that costs credits there, such as OpenSEO research, spends your credits with that vendor, the same as it would from any other client.