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Gumloop can browse the Nevermined Catalog and pay for services as a flow runs. You add one MCP connector, paste your Nevermined API key, and Gumloop does the rest. This is the per-host walkthrough; for the full tool surface and the safety model, see Using the Catalog from a harness.
Gumloop connects with a plain Nevermined API key, not the OAuth “approve a spending cap” flow that some assistants (Claude, ChatGPT) use. The key is your credential — it spends whatever its Nevermined account funds, so you set the budget on your account, not in Gumloop.

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Before you connect

1

A Nevermined account

Free, at nevermined.app.
2

A Nevermined API key

Create a plain API key in the app — Settings → Global NVM API Keys — for the environment you want, and send the whole string, prefix included (sandbox:… or live:…). A key minted by an OAuth flow can’t pay through the Router’s delegation routes, so use a plain one. See Get a Nevermined API key.
3

A way to pay

The key spends from one of two budgets you set up once: a Nevermined Subscription whose monthly credits a plain key can spend, or a spending delegation — a capped, revocable budget funded from your own wallet (Using the Catalog from a harness walks through it). Discovery is free and needs neither.
Start on sandbox, where you use testnet funds and nothing costs real money, before you point Gumloop at live.

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Add the Catalog to Gumloop

1

Open the MCP connector dialog

In Gumloop, go to Settings → Connectors, click the arrow next to Add Connector, and choose Add MCP Connector.
2

Point it at the server (Public URL)

Set Connection type to Public URL and paste the URL for the environment you want:
3

Set the authentication

Under Configure, set Authentication to Access Token / API Key and paste your Nevermined API key — Gumloop sends it as Authorization: Bearer <key> on every request, which is exactly what the Catalog MCP expects.
Use the Access Token / API Key field, not the Additional Header field. Gumloop’s docs note that Anthropic models drop custom headers, so an Authorization header added through Additional Header may not be forwarded — the Access Token / API Key field is.

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Your Nevermined API key

That key is your credential — there is no separate consent screen to approve. Keep the prefix: a live: key for mcp.live, a sandbox: key for mcp.sandbox. The key spends whatever its account funds — your Subscription credits, or a spending delegation funded from your wallet — so the budget and the audit trail live on your Nevermined account, not in Gumloop. Treat it like a password: never commit it or paste it into a shared chat. Every way to mint one: Get a Nevermined API key.

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Make your first paid call

Give a flow a task that needs a live, paid service, so the agent reaches for the Catalog tools rather than answering from memory.
1

Browse for free

Have the flow call a free discovery tool first — list the Nevermined catalog categories, or search the catalog for a weather service. Discovery needs no payment.
2

Let it buy

Then have it pay a service by slug — buy the service <slug> and return the response. The paid call draws on your subscription credits or delegation and returns the merchant’s response.
If the flow answers without paying, it answered from its own knowledge — have it call a discovery tool first and ask for something only live data can answer. More on phrasing: Catalog MCP tips.

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Disconnect or rotate the key

  • Stop the credential (Nevermined side). The key is the credential, so to cut Gumloop off, rotate or delete the key in the app (Settings → Global NVM API Keys) — every call with the old key then fails. To cap spending without revoking the key, revoke the delegation it spends from in Payment methods; discovery still works.
  • Remove the connector (Gumloop side). In Settings → Connectors, open the Nevermined MCP connector and remove it.
To spend again, paste a fresh key; if you revoked the delegation, create a new one — see Using the Catalog from a harness.

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Next

Using the Catalog from a harness

The full plain-key playbook — discovery, delegations, and the safety rules.

Catalog MCP — full reference

Every tool, the API-key header, and every refusal code.