Use Wavegrain from n8n

n8n has two nodes that call an MCP server such as Wavegrain:

Node	What it does	Needs a model
MCP Client Tool	Gives an AI Agent node the Wavegrain tools; the model decides which to call.	Yes
MCP Client	Calls one named Wavegrain tool with fixed inputs, like any other node.	No

This is the other direction from n8n's own "instance-level MCP", which lets AI apps call your n8n workflows.

We tested both nodes on n8n 2.44.7 against a local Wavegrain: they listed slideshows with list_slideshows and priced a slideshow with estimate_cost, which spends nothing.

The rule: a workflow never approves or posts

An n8n workflow makes drafts and Calendar slots. You approve each post in Wavegrain, and Wavegrain posts it. Give the workflow's key only the permissions it needs, never more, and limit the node to the tools the workflow uses.

1. Make an access key

In Wavegrain, open Settings and find Connect an AI agent. Make a key named "n8n" with:

• read to look at brands, slideshows and the Calendar;
• write only if the workflow puts slideshows on the Calendar;
• generate only if it makes slideshows, with a daily credit limit you are happy to spend.

2. Add the credential in n8n

Create a Bearer Auth credential and paste the key as the token.

3. Configure the MCP Client Tool node

Add an AI Agent node, attach a chat model, then attach an MCP Client Tool node:

Field	Value
Endpoint	https://wavegrain.com/api/mcp
Server Transport	HTTP Streamable
Authentication	Bearer Auth, with the credential from step 2
Tools to Include	Selected, then tick only the tools the workflow needs
Options, Timeout	120000 (generation calls can take a minute)

n8n names each tool after the node, so a node named "Wavegrain" gives the model Wavegrain_list_slideshows and so on.

To call one tool without a model, use the MCP Client node instead: the same endpoint, transport and credential, then pick the tool (for example estimate_cost) and give its input as JSON, such as {"slideCount": 6}. Its output holds the tool's answer in structuredContent.

4. Import the weekly plan workflow

Download the example workflow and import it in n8n (Workflows, Import from File).

Every Monday at 09:00 it asks Claude to plan five slideshows for one brand: it reads the brand brief and the Calendar, prices the work with estimate_cost, makes the slideshows with generate_slideshow within a credit limit, and puts them on the Calendar with schedule_slideshow. You open Wavegrain, look at the week, and approve the posts you want.

After importing:

1. Put your brand's name in the agent's prompt, and your time zone.
2. Pick your Bearer Auth credential on the Wavegrain node, and an Anthropic credential on the Claude node.
3. If your Wavegrain address is not https://wavegrain.com, change the endpoint.
4. Run it once by hand and check the Calendar in Wavegrain.

The node lists only the ten tools the plan needs. It has no tool that approves, and the key has no permission to approve.

Troubleshooting

Symptom	Cause
401	The key is wrong, revoked or expired, or the credential is not Bearer Auth.
403 with insufficient_scope	The key lacks the permission the tool needs. Each tool's description names it.
406	A proxy changed the Accept header; the server needs application/json, text/event-stream.
A tool answers with a sentence and isError	Wavegrain refused, for example over maxCredits. The sentence says what to change.
A self-hosted n8n in Docker cannot reach a local Wavegrain	Use http://host.docker.internal:<port>/api/mcp, not localhost.