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Flowise MCP Server Config: Custom MCP, Keys and Agents

Connect a remote Flowise MCP server: the Custom MCP JSON config, a Bearer key kept in a variable, which transports work, and Tool Agent or Agentflow setup.


Published · Updated · 6 min read

Cover image: X tools in a Flowise agent

Flowise MCP support comes from the Custom MCP tool node: paste a JSON config with the server's url and headers, then pick its actions.

This guide adds Weir, so your Flowise agents can search X (Twitter) and read posts, threads and profiles. Weir only reads, so it never posts as you. We run Weir.

{
  "url": "https://api.weirapp.io/mcp",
  "headers": {
    "Authorization": "Bearer {{$vars.weirKey}}"
  }
}

Flowise MCP server config: add Weir in five steps

You need a free Weir account and a Flowise where you can edit flows.

We read Flowise 3.1.4, released 29 July 2026: its docs and its source.

  1. Create a keyIn your Weir dashboard, open API keys and create one. It starts with weir_live_ and shows once.
  2. Store itIn Flowise, open Variables and add weirKey, type Static, with the key as its value.
  3. Add the nodeIn a Chatflow, drag Custom MCP from Tools (MCP) onto the canvas. Paste the config above.
  4. Load the actionsRefresh Available Actions, then pick SEARCH_X and GET_USAGE.
  5. Connect an agentWire the node into the Tools input of a Tool Agent.

Write {{$vars.weirKey}} with no spaces. Flowise's pattern skips {{ $vars.weirKey }}, so Weir would get the braces and answer 401.

Static or Runtime? A Static variable keeps the key in Flowise's database as plain text. A Runtime variable reads the environment variable of the same name, so name it WEIR_API_KEY and set that on the server.

Which Flowise MCP transport works with Weir?

Streamable HTTP, and Flowise picks it for you.

Transport Flowise 3.1.4 Weir
Streamable HTTP Tried first for any url Served
SSE Fallback if that fails Not served
stdio Self-hosted, opt-in Not needed

There's no transport field to set. Flowise's source connects to any url with Streamable HTTP and falls back to SSE only on an error.

So when a Weir connection fails, the message may come from the SSE retry, not the first attempt. Check the key before you chase the transport.

Custom MCP or Custom MCP Server: which Flowise MCP node?

Use Custom MCP Server on Flowise 3.1.3 or later, and Custom MCP on anything older.

Flowise 3.1.3, released 25 June 2026, added a Custom MCP Servers tab under Tools. You add Weir there once:

  • Server URL is https://api.weirapp.io/mcp, with Weir as the Server Name.
  • Authentication is Custom Headers: Header Key Authorization, Header Value Bearer plus your key.
  • Add & Connect checks the server and lists its tools.

Flowise encrypts those header values and shows them masked. Then any flow can pick Weir in a Custom MCP Server node, and you rotate the key in one place.

How to attach Flowise MCP tools to an agent

Flowise MCP tools work like any other tool node, so they plug into the agent that runs your flow.

  • Chatflow. A Tool Agent takes the node in its Tools input, next to a Tool Calling Chat Model and Memory.
  • Agentflow. In an Agent node, add a tool under Tools and choose Custom MCP or Custom MCP Server. Then paste the config or pick Weir, and select actions.
  • One fixed call. An Agentflow Tool node runs a tool with inputs you set and no model choosing. Give it one action, such as SEARCH_X.

A Flowise MCP example: has @FlowiseAI posted lately?

Ask your agent:

Use search_x: has @FlowiseAI posted on X since 1 September? Skip replies and reposts.

The model should call search_x. We ran that call through Weir's MCP server on 24 October 2026:

→ search_x {"fromUsers": ["FlowiseAI"], "query": "-filter:nativeretweets",
            "onlyOriginal": true, "since": "2026-09-01T00:00:00Z", "limit": 1}
← 0 posts · 1 credit (1 + 0 × 1) · nextCursor null

X search found no original posts, so the agent should answer no. That's what X returned for us, not proof the account is idle.

The empty search still cost the 1-credit call fee. A null nextCursor means there's nothing more to fetch.

1credit for our empty search
2credits for a 1-post search
11credits for a 10-post search
5,000free Weir credits every month

Weir bills 1 credit per call plus 1 per X post, and failed calls are free. Packs start at $5 for 25,000 credits and never expire, as of October 2026. See every rate on our pricing page.

Can Flowise be an MCP server too?

Yes, since 3.1.3. Open a chatflow's Configuration, then MCP Server under Advanced, and turn on Expose as MCP Server. Other MCP clients get a Streamable HTTP endpoint and a Bearer token.

What we haven't tested

We can't run Flowise here. This guide comes from Flowise's docs and source, plus a real call through Weir's MCP server.

  • The Custom MCP node against Weir. Its client matches what Weir serves, but we haven't run a flow.
  • The Custom MCP Server tab. We read its form in the source, not in a live Flowise.

If it doesn't work

  • Available Actions says "No Available Actions". Check the variable name and the key, then refresh.
  • The agent never calls Weir. Tick the actions you need. An unticked action never reaches the agent.
  • A tool returns 401. The variable didn't resolve. Remove spaces inside the braces.
  • A tool returns 402. Your Weir credits ran out, and retrying won't help.

When not to use Weir

  • The agent has to post or DM. Weir is read-only.
  • Price per post matters most. TwitterAPI.io lists $0.15 per 1,000 tweets as of October 2026, less than our $5 pack.
  • You need a guarantee. Weir isn't licensed by X or affiliated with it, so access can change.

FAQ

Can Flowise sign in to MCP servers with OAuth?

Not in 3.1.4. Its Custom MCP Server form offers No Authentication or Custom Headers, and the Custom MCP node sends the headers you write. Weir takes a key in a header, so you don't need sign-in.

Is the Flowise MCP client the same in Chatflow and Agentflow?

Yes. Both use the same Custom MCP and Custom MCP Server nodes, so one config works in a Tool Agent and in an Agent node.

Does Flowise MCP support stdio servers?

On self-hosted Flowise, if you opt in. Flowise 3.1.4 runs a command only when CUSTOM_MCP_PROTOCOL is stdio and the command is on CUSTOM_MCP_ALLOWED_COMMANDS. Weir is remote, so skip that.

Can Flowise post to X through Weir?

No. Weir only reads public X data, so nothing can post, like or follow through it.

Sources

All checked on 24 October 2026:

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