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Enable your agent session

Give the agent a session sub-wallet so it can use paid tools — web search, scraping, price data, or custom x402 endpoints — autonomously, and cap the spend.

Agent sessionToolsx402

To let the agent act on its own — searching the web, scraping, pulling data — you enable an agent session: a small sub-wallet that lives in your browser and pays for tools per call over the x402 standard, with no popup each time. It’s separate from your main inference balance, you control which tools the agent may use, and the amount you load is the most it can ever spend.

Halo is in alpha on Base mainnet with real USDC. Tools run in Agent mode (see chat vs agent mode).

How x402 payments work

x402 turns the “402 Payment Required” HTTP status into a real payment rail: a tool answers 402 with a price, your client signs an off-chain USDC authorization (EIP-3009), and Halo’s facilitator submits it — so a tool call is just “request → pay → response,” with no API keys or subscriptions on your side.

The Tools & permissions panel

Open Setup → Tools on the Agent page to reach Tools & permissions — “what the agent may use, and what it may spend without asking.” Each paid tool has a three-way policy:

  • Auto — run freely, within your spend threshold.
  • Ask — ask you before each run.
  • Off — hide the tool from the agent entirely (disable it).

There’s also a global guard: always ask before any single call over $X, even for tools set to Auto. Built-in paid tools include web_search, web_scrape, coingecko_price, messari, and nansen, each with its own per-call price; free built-ins (like recall and remember) don’t cost anything.

Add a custom tool

Expand + Add a custom tool (x402 endpoint) and provide:

  • Name (e.g. crypto_prices)
  • Description — what it does and the args to pass
  • URL — your x402-compatible endpoint
  • Method — POST (JSON body) or GET (query params)

Then Add tool. Custom tools are tagged “custom,” default to the Ask policy, and are capped at a small per-call ceiling for safety. During alpha, custom tools are for data / information / scraping endpoints only — not actions or transactions.

The tool sub-wallet

Tools are paid by a dedicated sub-wallet (a separate in-browser key), so the agent can pay per call without touching your main balance:

  1. Click Enable autonomous tools and approve once.
  2. Fund the sub-wallet with a few dollars of USDC (this uses a gasless transfer). The amount you load is the most that can ever be spent — keep it small; that’s your cap.
  3. Withdraw sweeps unused funds back to your main wallet (no popup), and you can Disable it anytime.

The sub-wallet key lives in memory only for the page session and is never stored.