H Company connects through a plain Nevermined API key, not the OAuth “approve a spending cap” flow that some assistants (Claude, ChatGPT) use. The key stays in your backend and is never handed to the agent; it spends whatever its Nevermined account funds, so you set the budget on your account, not in H Company.
See it in action
To ground the setup, here is an agent we built and ran on H Company: a recall checker. You hand it a product and it returns a sourced safety brief, discovering and paying for the services it needs on its own. It is a saved Runner H Agent (recall-checker, model holo4-27b) with the Catalog wired in as its tools, the same shape an n8n builder gets from the MCP Client Tool node.
A recall-checker agent on H Company, paid per call, built on the Nevermined Catalog: given one product, the agent discovers and pays for a public-safety-recall lookup and a model to write the brief, and returns a sourced risk assessment. Every call is paid per use from the account's credits.
What one run looks like
On a run the agent calls the Catalog more than once. For each part of the brief it searches for a service that fits, pays for that one call, and moves on, all against the same budget.
The agent then emitted a sourced HIGH-risk brief: the active CPSC recall, the hazard, the remedy, a recommended action, and the source link. About 165 credits in total, all from the account’s subscription credits, with no stablecoin spend. It paid for the two calls its task needed and nothing else. The Catalog tool calls in this run were resolved by the integration’s own backend, the method shown in Add the Catalog to H Company.
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:…). Use a plain key rather than one from an OAuth consent flow: your backend needs a static bearer token and has no consent step to run. See Get a Nevermined API key.3
A way to pay
The key spends from your Nevermined credits: the free credits a new account gets when it signs up with a verified email, top-up packs, or a Nevermined Subscription’s monthly allowance. It can also spend from a capped, revocable delegation funded from your own wallet (Using the Catalog from a harness walks through it). Discovery is free and needs neither.
4
An H Company agent
Access to H Company’s Agents API (
https://agp.eu.hcompany.ai/api) with your H Company API key, so you can define an agent and run a session.Start on sandbox, where you use testnet funds and nothing costs real money, before you point H Company at live. The Catalog is Live-only for payment: sandbox discovers services but cannot settle a real one, so run the money path on live with a small cap.
Add the Catalog to H Company
Runner H agents call tools, and a tool can be client-executed: the agent emits the call, pauses, and your integration runs it and sends the result back. That is where the Catalog lives. You give the agent a couple of Catalog tools, and your backend resolves each call against the Catalog MCP with your Nevermined API key. The key stays in your backend, so the agent never holds it. Your backend talks to the Catalog MCP endpoint for the environment you are on:1
Define the agent with Catalog tools
Create an agent (
POST /v2/agents, or pass it inline per session) whose tools are client-executed definitions for the Catalog, for example one to search services and one to pay a service by slug. Run sessions against it by name.2
Run a session and watch for tool calls
Start the session (
POST /v2/sessions) with the task, then poll GET /v2/sessions/{id}/changes. When the agent calls a tool, the session turns to awaiting_tool_results and the pending calls arrive with their name and arguments.3
Resolve each call against the Catalog
Call the Catalog MCP (the URL above) with your key as
Authorization: Bearer <your Nevermined API key>, then post the result back with POST /v2/sessions/{id}/tool_results. The agent resumes and, once it has what it needs, returns its answer. Keep the prefix: a live: key for mcp.live, a sandbox: key for mcp.sandbox.The budget is the guardrail
An agent runs with no human watching each call, so the account’s limits do the work a person would. The key spends only what its Nevermined account funds, enforced on Nevermined’s side, not inside H Company. With a plain key the Commerce MCP pays from your credits first whenever they can cover a call, and from a delegation otherwise, so know which one an agent is spending and what actually bounds it.- A delegation is a hard, revocable cap. Fund it once and its cap is the ceiling for every call paid from it. Revoke it any time, in one action, from Payment methods, and the next delegation-funded call fails. For a hard per-agent ceiling, have your backend send
funding: "delegation"on every pay call, so the delegation cap is the only bound no matter what credits the account holds. (Running the agent on a separate account with no credits works too, but welcome credits and a subscription’s allowance arrive on their own, so the explicit lever is simpler.) - Credits have no cap beyond your balance. There is no daily, per-service or per-key limit, and with top-ups on, a call that runs short charges your card for a 10,000-credit pack, up to a monthly limit you set. Revoking a delegation does not stop credit spend; the Nevermined-side stop for credits is rotating or deleting the key and turning top-ups off.
- Keep the stop within reach. Treat the backend secret that stores the key as spending authority, and know the lever before you need it: the key and top-ups for credits, the delegation cap for delegated calls.
Make your first paid call
Give the agent a task that needs a live, paid service, so it reaches for the Catalog tools rather than answering from memory.1
Browse for free
Ask the agent to call a free discovery tool first, for example list the Nevermined catalog categories or search the catalog for a recalls service. Your backend resolves the call against the Catalog, and discovery needs no payment.
2
Let it buy
Then ask it to pay a service by slug, for example buy the service
<slug> and return the response. Your backend runs the pay call against the Catalog; it draws on your Nevermined credits or delegation and returns the merchant’s response. Payment is live-only: on sandbox the only payable services are the two testnet test merchants, mpp-dev-paid-ping and x402-org-protected, so make your first real purchase on live with a small cap.Disconnect or rotate the key
- Stop the credential (Nevermined side). The key is the credential, so rotate or delete the key in the app (Settings → Global NVM API Keys); every call made with the old key then fails, your backend’s included. That is the only Nevermined-side stop for credit spend, so also turn off top-ups. To cap delegation-funded spend without revoking the key, revoke the delegation in Payment methods; discovery still works.
- Stop resolving calls (H Company side). Remove the Catalog tools from the agent, or retire the agent, so it can no longer reach the Catalog, and remove the key from your backend.
Next
What the Catalog is
The marketplace of pay-per-call services your agent can discover and buy.
Build an Outcome
Describe a result and a budget; the Catalog composes and pays for the services, the pattern behind the recall checker above.
Catalog MCP reference
Every tool, its arguments, the API-key header, and every refusal code.
Using the Catalog from a harness
The full plain-key playbook: discovery, delegations, and the safety rules.