# MCP tools
CKEditor AI can call tools on external MCP servers, such as the servers published by your wiki, your ticketing system, or your product catalog. Connect one, and the model looks up current information in that system, or acts in it, during a conversation.
This page covers the servers you define in the service configuration. You give each server a URL, a way to authenticate, and, if you want, a list of the tools the model must not call. For what users see in the editor, and for registering a server through the admin REST API instead, see [MCP tools](../../guides/ckeditor-ai/extensions/mcp-tools.md).
A connected server offers **tools** and **resources**. CKEditor AI calls the tools during a request. An administrator attaches the resources to a context as files. One connection serves both.
> **Note**
>
> The two sets of server names share one namespace, and the service configuration has priority. The REST API rejects a name that the configuration already uses. If the configuration later takes a name that the API added first, the configuration entry replaces the API entry.
## Two ways to connect a server
* **Admin API** – an administrator registers a server for one environment at runtime, with no redeploy. The endpoints are on the [MCP tools](../../guides/ckeditor-ai/extensions/mcp-tools.md) guide page.
* **Service configuration** – the `mcp_servers` object described on this page. It applies to every environment, or to the ones you list, and changing it means redeploying.
Chat and Document Processing use servers connected either way. Reviews and actions do not use MCP tools. Document Processing runs with no signed-in user, so it skips servers that need OAuth.
## Configuration
Each server is an entry in the `mcp_servers` object, keyed by its name. The key is the name you use for the server afterwards, and it prefixes the names of the server’s tools. Only `url` is required:
* `url` (required) – the URL of the MCP endpoint of the server. The service opens the connection over the [Streamable HTTP transport](https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#streamable-http), so this URL must be reachable from the network your containers run in.
### Basic setup
**JSON**
```json
{
"mcp_servers": {
"": {
"url": ""
}
}
}
```
**Environment variable**
Pass the same object as a JSON string in the `MCP_SERVERS` variable:
```bash
docker run --init -p 8000:8000 \
# ... other environment variables ...
-e MCP_SERVERS='{"":{"url":""}}' \
docker.cke-cs.com/ai-service:[version]
```
The same configuration split over several lines with a shell variable:
```bash
export MCP_SERVERS='{
"": {
"url": ""
}
}'
docker run --init -p 8000:8000 \
# ... other environment variables ...
-e MCP_SERVERS="$MCP_SERVERS" \
docker.cke-cs.com/ai-service:[version]
```