MCP server for agents

The voidcash MCP server gives an AI agent its own private HYPE account on Elysium. Any agent that speaks the Model Context Protocol over stdio, such as Claude Code, Claude Desktop or Cursor, can use it.

The agent holds HYPE in encrypted notes only it can read, pays without showing its address, and gets paid at a private address. It signs with its own key, locally: there is no wallet to click through. Private actions need no public HYPE: their gas is paid from the notes.

Why agentsCopy Anchor Link

An agent that pays on-chain shows everything: which services it uses, how much it spends, and, for a trading agent, its strategy. With voidcash:

• Its balance and its payments stay private. A private send shows neither side nor the amount.
• It can get paid without revealing its address, at a private address.
• You can give it a budget without giving it a wallet: send it a payment link. It can spend what the link holds and nothing more, and you can take back what it does not claim.
• Every private send comes with a proof: a link that shows the recipient and the amount of that one payment, for invoices and receipts.

Set it upCopy Anchor Link

The server is the package @voidcash/mcp in the voidcash repository (packages/mcp). It is not published on npm: build it from the repository and run the build with Node.js 22 or later, on the agent's machine. The key never leaves it.

VOIDCASH_APP_URL=https://voidcash.io \
VOIDCASH_BUNDLER_URL=https://bundler.voidcash.io \
VOIDCASH_INDEXER_URL=https://indexer.voidcash.io \
VOIDCASH_EXPLORER_URL=https://elysium.kinetiq.xyz/explorer \
pnpm --filter @voidcash/mcp build

Claude CodeCopy Anchor Link

claude mcp add voidcash \
  --env VOIDCASH_PRIVATE_KEY=0x... \
  --env VOIDCASH_MAX_HYPE=10 \
  -- node <repository>/packages/mcp/dist/main.js

Claude Desktop, Cursor and other clientsCopy Anchor Link

{
  "mcpServers": {
    "voidcash": {
      "command": "node",
      "args": ["<repository>/packages/mcp/dist/main.js"],
      "env": {
        "VOIDCASH_PRIVATE_KEY": "0x...",
        "VOIDCASH_MAX_HYPE": "10"
      }
    }
  }
}

To check a build before giving it a real key, run npx tsx test/smoke.mts from packages/mcp, with SMOKE_COMMAND="node dist/main.js" to test the build rather than the sources. It starts the server over stdio with a fresh key in read-only mode and calls the reading tools on Elysium.

SettingsCopy Anchor Link

With VOIDCASH_APP_URL=https://voidcash.io, the key derives the same private account as the app does: importing it into a browser wallet and opening voidcash.io shows the same balance and history.

ToolsCopy Anchor Link

get_status, get_history, get_pool_stats, payment_link_status, quote_unshield, get_private_address and verify_payment only read. Errors come back as tool errors the agent can read.

The tools handle HYPE. Every amount they take or return is in HYPE, and get_status and get_history show the HYPE balance, HYPE activity and HYPE exits. Notes of a listed token that the agent's key holds, such as VOID sent to its address, do not appear in the results. With the same VOIDCASH_APP_URL as the app, the same key opens the same account in the app, which shows and moves them.

CostsCopy Anchor Link

The exit fee goes to the fee collector: half to the team, half to buying VOID and burning it. An unshield paying out more than the vault's large-exit threshold (1,000 HYPE at deployment) is paid 24 hours later, through release_exit. get_status shows the threshold and the current gas estimate. A link must hold more than twice the gas its claim pays. See Fees.

How the key is usedCopy Anchor Link

The key is an ordinary secp256k1 key. Its address holds the agent's public HYPE. The server signs with it locally, with no prompt:

• The key-derivation message, once per process, to derive the privacy keys exactly as the app does. No transaction, no HYPE. The privacy keys are kept in memory only.
• A spend signature (EIP-712, under the vault's domain) for every private action. The proof checks it, so the privacy keys alone cannot move the agent's HYPE.
• The link-key message, once per process, when the agent creates its first payment link.
• Public transactions: shield, register and release_exit.

Proofs are made on the agent's machine. Private actions go to the bundler as ERC-4337 operations whose sender is the vault, so the agent's address does not appear in them.

LimitsCopy Anchor Link

• VOIDCASH_MAX_HYPE caps a single shield, send_private, pay_private_address, create_payment_link, unshield (with all, the private balance) and collect_private_address (what waits there). Claiming a link, registering and releasing an exit are not capped: they bring HYPE in or pay an exit already decided.
• Read-only mode refuses every tool that signs or sends, with an error.
• No bundler means no private actions; reads, shield, register and release_exit still work.
• The public bundler accepts 120 requests a minute per address, 20 of them estimates or sends: one private action makes about 35. See Deployments.
• A spend uses the agent's two largest notes of one tree. If they do not cover an amount plus the gas, the action is refused with the reason, even when the whole private balance would.

Keep it safeCopy Anchor Link

• The key is the account. Whoever has it can spend everything the agent holds. Give the agent a key of its own, fund it with what it needs, and set VOIDCASH_MAX_HYPE.
• Payment links are bearer instruments. The agent should send them only to the payee, never post them.
• Unshields name a recipient. To keep an exit apart from the agent, it should unshield to a new address, not its own.