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D20DAO Verifiable Randomness

Official registry Developer tools

Verifiable VRF draws on Arc, 0.05 USDC each. On Robinhood Chain, integrate on chain with the SDK.

Source code Website Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

NPM package @d20dao/mcp
Claude Code 
claude mcp add d20dao-verifiable-randomness -e 'D20_DAILY_LIMIT_USDC=<D20_DAILY_LIMIT_USDC>' -e 'D20_NETWORK=<D20_NETWORK>' -e 'D20_PAY_CHAIN=<D20_PAY_CHAIN>' -e 'D20_WALLET_ADDRESS=<D20_WALLET_ADDRESS>' -e 'D20_CIRCLE_CLI=<D20_CIRCLE_CLI>' -e 'D20_MCP_HOME=<D20_MCP_HOME>' -- npx -y @d20dao/mcp@0.1.2
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "d20dao-verifiable-randomness": {
            "command": "npx",
            "args": [
                "-y",
                "@d20dao/mcp@0.1.2"
            ],
            "env": {
                "D20_DAILY_LIMIT_USDC": "<D20_DAILY_LIMIT_USDC>",
                "D20_NETWORK": "<D20_NETWORK>",
                "D20_PAY_CHAIN": "<D20_PAY_CHAIN>",
                "D20_WALLET_ADDRESS": "<D20_WALLET_ADDRESS>",
                "D20_CIRCLE_CLI": "<D20_CIRCLE_CLI>",
                "D20_MCP_HOME": "<D20_MCP_HOME>"
            }
        }
    }
}

Environment variables

  • D20_DAILY_LIMIT_USDC Spending cap per UTC day in USDC (default 1; 0 turns paid draws off).
  • D20_NETWORK Arc Mainnet (default) or Arc Testnet.
  • D20_PAY_CHAIN Circle CLI chain code to pay from, such as ARC or BASE (default: first funded).
  • D20_WALLET_ADDRESS Agent wallet to pay from (default: the first one the Circle CLI lists).
  • D20_CIRCLE_CLI Path to the Circle CLI's dist/index.js (default: circle on PATH).
  • D20_MCP_HOME Folder for the daily spending record (default ~/.d20dao-mcp).

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. D20DAO MCP server
  2. Setup
  3. Tools
  4. Settings
  5. Safety
  6. Verify
  7. License

D20DAO MCP server

Verifiable randomness for AI agents: dice, coin flips, ranges, winners and shuffles, each one a VRF request on Arc with a proof anyone can replay. 0.05 USDC per draw, paid from your Circle Agent Wallet.

Draws run on Arc through the D20DAO x402 API. D20DAO also runs on Robinhood Chain, where there is no x402 API: a contract there requests randomness directly on chain, using @d20dao/vrf-sdk 0.6.2 and its integration guide.

Setup

  1. Wallet. Have your agent follow Circle's setup guide. It installs the Circle CLI, logs you in with an emailed code and creates an agent wallet. You accept Circle's terms yourself.

  2. Funds. Fund the wallet with USDC and deposit some into Circle Gateway, for example on Arc:

     circle gateway deposit --chain ARC --method direct --amount 1 --address <wallet>

    Arc, Polygon, Avalanche, Base, Arbitrum, Optimism, Unichain and Ethereum balances all work.

  3. Server. Add it to your client.

    Claude Code:

     claude mcp add d20dao -- npx -y @d20dao/mcp@0.1.2

    Claude Desktop, Cursor and others (mcpServers in the client's MCP config):

     { "mcpServers": { "d20dao": { "command": "npx", "args": ["-y", "@d20dao/mcp@0.1.2"] } } }

    On Windows, use "command": "cmd" with "args": ["/c", "npx", "-y", "@d20dao/mcp@0.1.2"] if the client cannot start npx directly. Pin the version, since the server runs with your Circle session.

Ask your agent to call setup_status; it names the next step until everything is ready.

Tools

ToolCostDoes
draw0.05 USDCraw, coinFlip, dice (up to 128), range, chooseOne, chooseMany, shuffle (up to 256 items). Returns the result with request, fulfillment and proof links.
get_resultfreeReads a draw by paymentId or a request by requestId.
setup_statusfreeChecks the CLI, login, wallet, Gateway balance and today's spending.

An optional seed (up to 64 bytes) is bound on chain to the draw, so a raffle can name its round before the result exists. Give each separate draw its own seed: an identical draw within five minutes returns the earlier one without paying.

A draw usually answers in about ten seconds, but it can take longer. If your client's tool timeout is short (60 seconds is a common default), raise it; a retry after a timeout returns the same draw rather than paying twice.

Settings

VariableDefault
D20_DAILY_LIMIT_USDC1Spending cap per UTC day, shared by every server process of the user. 0 turns paid draws off.
D20_NETWORKmainnettestnet uses the Arc Testnet API and a testnet CLI login (circle wallet login <email> --testnet).
D20_PAY_CHAINfirst fundedCircle CLI chain code to pay from, such as ARC or BASE.
D20_WALLET_ADDRESSfirst agent walletAgent wallet to pay from.
D20_CIRCLE_CLIcircle on PATHPath to the CLI's dist/index.js.
D20_MCP_HOME~/.d20dao-mcpWhere the spending record is kept.

Safety

  • The server holds no keys. The Circle CLI signs, and your Circle wallet limits apply. It never accepts Circle's terms for you: CIRCLE_ACCEPT_TERMS is kept out of the CLI it runs, and DO_NOT_TRACK is set so your item labels stay out of the CLI's telemetry.
  • It pays only api.d20dao.org (or api-testnet.d20dao.org) and never more than 0.05 USDC per draw. If the CLI ever reports another seller, that draw comes back with a warning and paid draws stop until you delete halt.json from the server's home folder.
  • Each draw reserves its price in the daily record before paying; if the record cannot be written, it does not pay.
  • A draw that is still pending is finished for free with get_result. If the answer is lost after payment, the server resends the payment the CLI signed, which the API honours at most once.
  • A result says charged: false only when that is known. When it says unknown, do not draw again; check with get_result or the wallet.
  • draw is marked as a tool with side effects, so clients ask before running it unless you allow it.

Verify

Every result links its request and fulfillment transactions and a proof page. Replay the proof yourself with @d20dao/vrf-sdk 0.6.2 or later; see verification and the agent API guide.

License

MIT

Frequently asked questions

What is D20DAO Verifiable Randomness?

Verifiable VRF draws on Arc, 0.05 USDC each. On Robinhood Chain, integrate on chain with the SDK.

How do I install D20DAO Verifiable Randomness?

It runs on your machine. In Claude Code: claude mcp add d20dao-verifiable-randomness -e 'D20_DAILY_LIMIT_USDC=<D20_DAILY_LIMIT_USDC>' -e 'D20_NETWORK=<D20_NETWORK>' -e 'D20_PAY_CHAIN=<D20_PAY_CHAIN>' -e 'D20_WALLET_ADDRESS=<D20_WALLET_ADDRESS>' -e 'D20_CIRCLE_CLI=<D20_CIRCLE_CLI>' -e 'D20_MCP_HOME=<D20_MCP_HOME>' -- npx -y @d20dao/mcp@0.1.2. For other clients, paste the JSON configuration from this page into their MCP settings.

Does D20DAO Verifiable Randomness need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is D20DAO Verifiable Randomness open source?

Yes. Its code is on GitHub under the MIT license.

Who maintains D20DAO Verifiable Randomness?

It is published by d20dao. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.