Description

n8n-nodes-scalable-capital

An n8n community node for Scalable Capital,
talking to their official MCP endpoint at https://mcp.scalable.capital/mcp.

Read-only by default. See Safety — this is not incidental, it mirrors
a guarantee Scalable’s own tooling makes.

> Not affiliated with or endorsed by Scalable Capital. This project is not
> investment advice.

Why MCP and not the CLI

Scalable also ship an official CLI, scalable-cli.
It is the better tool at a terminal, but a poor fit for n8n. Its own capability
report says so:

$ sc capabilities --json | jq .data.auth
{ "modes": ["device"], "noninteractivemodes": [] }

There is no non-interactive login. A node shelling out to sc would need a
human-refreshed broker session living inside the n8n container. The MCP endpoint
is a network call with OAuth refresh tokens (offline_access is advertised), which
is what a workflow engine can actually keep alive.

Operations

Version 2 groups the server’s 39 tools into resources and gives every tool real
fields, derived from the input schema the server publishes:

| Resource | Tools | Example |
| — | — | — |
| Account | 3 | List Accessible Portfolios |
| Portfolio | 6 | Get Portfolio Holdings, List Portfolio Transactions |
| Portfolio Group | 7 | List Portfolio Groups |
| Security | 5 | Search Securities, Get Security Quote |
| Order | 6 | Preview Buy Order |
| Savings Plan | 5 | List Savings Plans |
| Watchlist | 3 | List Watchlist Items |
| Price Alert | 3 | List Price Alerts |
| Overnight Savings | 1 | Get Overnight Summary |
| Advanced | — | Execute Tool, List Tools |

Required arguments are ordinary fields. Optional ones sit under **Additional
Fields**. Types come from the schema: pageSize is a number bounded 1..100,
venue is a dropdown of gettex/xetra/eix, list arguments take a
comma-separated string. Only the trading tools keep a JSON field, for the
oneOf unions that describe quantity and order type — flattening those would
mean inventing a shape the server does not accept.

Advanced keeps the old behaviour: pick any tool by name and pass raw JSON.
That dropdown is still filled live from tools/list, so a tool Scalable adds
tomorrow is usable before this node is regenerated.

Version 1

Nodes already placed in a workflow stay on version 1 and keep the raw
Tool Name + Arguments pair. Nothing about them changes. test/built/node.test.mjs asserts
that, field by field, against the built output.

Regenerating the catalogue

nodes/ScalableCapital/tools.generated.ts is generated from
scripts/tools.snapshot.json, which is a copy of the server’s own tools/list
reply:

$ npm run generate
39 Werkzeuge in 9 Ressourcen: …

To refresh the snapshot, run the node itself with Advanced → List Tools and
save the result. The generator cannot fetch it: the endpoint needs OAuth, and the
refresh token rotates on every use. If Scalable adds a tool that no resource rule
matches, the generator fails rather than guessing — CI runs it and rejects a
snapshot that drifted from the generated file.

Safety

Scalable’s CLI declares this for every trade and savings-plan command:

{ "mode": "twophaseconfirmation",
  "forbidautomaticphase2execution": true,
  "confirmationmustbeseparatestep": true }

This node keeps that promise. Execute Tool refuses any tool that is not
read-only, using the server’s own readOnlyHint / destructiveHint annotations
when present and a conservative name heuristic when they are absent. Overriding it
requires ticking Allow Write Operations per node, and you should only do that
where a person confirms each run.

Additional protection worth configuring at the CLI level (independent of n8n):
[tradecontrols] with allowedisins, deniedisins and maxorder_notional.

Authentication

Scalable Capital only registers loopback redirect URIs. Measured against
their registration endpoint on 2026-08-26:

$ curl -sX POST https://mcp.scalable.capital/register -H 'Content-Type: application/json' 
    -d '{"redirect_uris":["https://n8n.example.com/rest/oauth2-credential/callback"], ...}'
{"error":"invalidredirecturi",
 "error_description":"Web clients may only register exact redirect URIs from the approved SaaS allowlist."}
$ ... -d '{"redirect_uris":["http://127.0.0.1:8765/callback"], ...}'
201  {"client_id":"..."}

So n8n’s own OAuth2 credential cannot be used: its callback is a server-side web
URL. The browser step happens once on your machine instead, and the node handles
the refresh — which needs no browser.

Get a refresh token (once)

node scripts/get-refresh-token.mjs

It registers a loopback client, opens the browser for the Scalable login, and
prints a Client ID and a Refresh Token. It runs locally; the values only
ever appear in your own console.

Fill in the credential

| Field | |
| — | — |
| Client ID | from the script |
| Refresh Token | from the script — the seed only, see below |
| Access Token | leave empty when you have a refresh token |
| MCP Endpoint | https://mcp.scalable.capital/mcp |
| n8n API URL | optional — enables the write-back below. An address n8n itself can reach, such as the in-cluster service http://n8n.my-namespace.svc.cluster.local:5678. A public URL may sit behind a login proxy that answers the API with a redirect instead of data. |
| n8n API Key | optional, needs the credential:update scope (n8n 2.4+) |

Use Test in the credential: it performs the refresh and a real initialize
against the MCP server, so a green result means the whole chain works. Note that
this consumes one rotation, like any other refresh — see below.

Order matters when you use the write-back: save the credential once with the API
URL and key, then run the script with N8NCREDENTIALID (the id in the address
bar while the credential is open) so it writes the fresh token straight into it.

Refresh token rotation

This server issues a new refresh token on every refresh and invalidates the
previous one. A token stored in the credential would therefore work exactly once.

The node keeps the current one in the workflow’s static data; the credential
field is only the seed. It also caches the access token until shortly before it
expires, so a run that happens inside that window performs no refresh at all and
burns no rotation.

Static data alone is fragile: n8n saves it only after a **successful run started
by a trigger or webhook**. A manual run, or a scheduled run that fails further
down, rotates the token and discards the new one.

Set n8n API URL and key to close that gap. After every rotation the node
writes the new refresh token back into its own credential via
PATCH /api/v1/credentials/{id}. It keeps a note of which credential value the
static data came from, so a newer credential (written back, or pasted by you)
always wins, and an invalid_grant on one token is retried once with the other.
A failed write-back is logged as a warning and does not stop the run.

Two gaps remain, both visible as invalid_grant:

• n8n tests the credential on every Save, and the test rotates the token. The

first Save writes the new token back. Saving the still-open dialog a second time
sends the old token again and overwrites it. Close the dialog after one Save.

• A manual run whose write-back fails keeps the new token only in memory.

The warning in the n8n log names it.

The script can skip the copy-paste as well:

N8NAPIURL=https://n8n.example.com N8NAPIKEY=... N8NCREDENTIALID=... 
  node scripts/get-refresh-token.mjs

The script runs on your machine, so this URL has to be reachable from there. If
the API is only open inside the cluster, tunnel it first (kubectl port-forward
svc/n8n 5678) and point N8NAPIURL at http://127.0.0.1:5678.

Without the write-back, two consequences remain:

• One credential per workflow. Two workflows sharing a credential each keep

their own static data and would invalidate each other’s token.

• If the static data is lost, re-run the script and paste a fresh seed. The

node then reports the server’s own message — invalid_grant means exactly this.

Obtain the token yourself. Scalable’s CLI README is explicit:

> For security and reliability, complete login yourself rather than via an AI agent.

Install

The package is scoped on purpose. An unscoped n8n-nodes-* name is free for
anyone to register on npm, and this repository is public — so the name is known
before it is claimed. A config that installs an unclaimed name from the public
registry hands the instance to whoever registers it first. A scope belongs to the
account and cannot be taken.

In n8n: Settings → Community nodes → Install, then @munin92/n8n-nodes-scalable-capital.

Manually:

cd ~/.n8n/nodes
npm install @munin92/n8n-nodes-scalable-capital

Status

Verified so far: TypeScript build, n8n community lint rules, and unit tests over
the Streamable-HTTP response parser (plain JSON, SSE, interleaved progress
notifications, JSON-RPC errors).

End-to-end in n8n 2.35.7 against a stub MCP server: the credential injects the
bearer token, the session id from initialize is carried on every later call,
SSE tools/list is parsed past an interleaved progress notification, and
structuredContent is unwrapped. The write guard was verified the only way that
counts — the stub recorded zero tools/call requests when a non-read-only
tool was invoked without the opt-in.

Not yet verified against a live account — that needs a token, which only the
account holder can obtain. If you run it, issue reports are welcome, especially
about the shape of tools/call results.

Development

npm install
npm run build
npm run lint     # @n8n/eslint-plugin-community-nodes, the current official ruleset
npm test

Linting uses ESLint 9 with @n8n/eslint-plugin-community-nodes. The older
eslint-plugin-n8n-nodes-base is not used: its rules disagree with the current
ones (it rewrites NodeConnectionTypes.Main to the string literal 'main',
which the current plugin rejects) and its documentationUrl autofix mangles a
URL into camelCase.

Once published, npx @n8n/scan-community-package @munin92/n8n-nodes-scalable-capital
runs n8n’s own security scan. It resolves the package from the registry, so it
cannot be run against a working copy.

Releases

Versioning and CHANGELOG.md are driven by semantic-release
from Conventional Commit messages: fix: bumps the patch, feat: the minor,
BREAKING CHANGE: the major. While the version stays on 0.x, a feat: bumps
the minor rather than declaring 1.0 — the node has not been verified against a
live account yet, so claiming a stable major would be untrue.

The Release workflow publishes on every push to main via npm
trusted publishing — no long-lived
token. It needs a trusted publisher configured on npmjs.com for this repository
and the workflow file release.yml, and the id-token: write permission the
workflow already declares. Do not hand-edit the version in package.json;
semantic-release owns it.

Publishing sets provenance, which is what n8n’s own scanner checks:

$ npx @n8n/scan-community-package @munin92/n8n-nodes-scalable-capital

Version 0.1.1 was published by hand to create the package (a trusted publisher
can only be configured on a package that already exists), so it carries no
attestation and will not pass that check. Every release from 0.1.2 on does.

License

MIT