How to connect Open WebUI to Anchor

Open WebUI

An admin completes the one-time setup (add the Anchor server, switch the model to native tool calling, install the Deferred Tools filter), then each user enables Anchor per-chat.

Admin setup

1. Go to Admin Panel → Settings → Integrations and click the + next to External Tool Servers.
2. Fill in the Add Connection dialog:
   • Type: MCP Streamable HTTP
   • Name: Anchor
   • ID: anchor
   • Description: Anchor is a shared workspace of files, tables and apps that your team and its AI agents can both read and edit.
   • URL: https://mcp.anchor.cc/mcp
   • Auth: OAuth 2.1
3. Click Register Client (top-right of the Auth row). Wait for the badge to flip from orange Not Registered to green Registered.
4. Click Save.

Enable write tools (Function Calling: Native)

By default a model may use the legacy Default (prompt-based) function-calling mode. In that mode it reliably calls read-only tools like ls and read_file but silently fails to call write tools like write_file, mkdir, and mv — so it looks like Anchor can only read. Switch the model to Native function calling so all tools work.

1. Go to Admin Panel → Settings → Models and select the model.
2. Under Advanced Params, click Show.
3. Set Function Calling to Native.
4. Click Save & Update.

Install the Deferred Tools filter

Open WebUI sends every tool's full schema with every message. This filter loads each schema only when the model needs it, cutting a typical message from about 29,000 prompt tokens to under 1,000.

1. Copy the filter source from anchor-cc/openwebui-dynamic-mcp: Copy deferred_tools.py to the clipboard
2. Go to Admin Panel → Functions and click Create.
3. Paste the source into the editor and click Save.
4. Turn the function's toggle on, then open its ⋯ menu and turn on Global so it applies to every model.

Per-chat usage

1. Start a New Chat.
2. Click Integrations in the message box (bottom-left), then Tools.
3. Turn Anchor on.
4. Pick a tool-capable model from the model dropdown (e.g. anthropic/claude-sonnet-4-5).
5. Ask "List my Anchor orgs." The first time, a sign-in window opens — use your Anchor account to connect.
6. Ask "What is Anchor, and what can I use it for?"