Liquidagentx402 MCP Server

Liquid Agent: money tools for AI agents (x402)

x402 money tools for AI agents. A one-signature USDC bridge from Base to 16 chains, the live Polymarket price to beat, a tokenized US stock basket from $1, and gas paid in USDC, plus free USDC and x402 debugging tools and a remote MCP server. No account, no API key, and the server never holds your keys.

Live API: https://api.liquidagent.ai · MCP: https://api.liquidagent.ai/mcp · Agent guide: https://api.liquidagent.ai/v1/guide · Status: https://api.liquidagent.ai/v1/status

x402 · AI agents · USDC bridge · CCTP · Polymarket · MCP · tokenized stocks · Base · ERC-4626 · ERC-8004 · agentic commerce · no oracle · self-custodial

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What is this?

The stock index part of Liquid Agent is an agent-native tokenized-stock index on Base. An autonomous agent (or a human) can:

• Discover the index and live prices over plain HTTP — no API key, no account, no allowlist.
• Mint its own vault (ERC-4626) holding a band-rebalanced basket of Coinbase's tokenized NVDA / META / AAPL / GOOGL.
• Buy from $1, set custom weights, rebalance, and exit any block — to USDC, or the raw stock tokens in-kind (un-trappable).

Every read is free. Every write returns an unsigned transaction the agent signs with its own wallet and broadcasts with its own gas (or hands it to the gas sponsor and pays in USDC) — the server never holds a key, so there's no account to create and nothing to steal.

Built for the agent economy: x402-discoverable, an A2A agent card, llms.txt / agents.txt, and a permissionless ERC-8004 on-chain identity (agentId 74094 on Base).

Why an agent picks this

Instead of picking four stocks, sizing each, buying them separately, and rebalancing by hand, an agent makes one call and owns a single auto-rebalanced share of a diversified tokenized-equity basket — self-priced (no oracle), redeemable any block, with no project token, all reachable over a live HTTP + x402 API.

MCP server (remote, no install)

Connect any MCP client (Claude, Cursor, ChatGPT, agent frameworks) by URL: https://api.liquidagent.ai/mcp (Streamable HTTP, no auth). Listed in the official MCP Registry as ai.liquidagent.api/liquid-agent and on Smithery.

claude mcp add --transport http liquid-agent https://api.liquidagent.ai/mcp

{ "mcpServers": { "liquid-agent": { "type": "streamable-http", "url": "https://api.liquidagent.ai/mcp" } } }

26 tools:

• Bridge: bridge_quote, bridge_prepare_payment, bridge_routes, bridge_status, bridge_referral_earnings
• Stocks: stocks_basket, stocks_portfolio, stocks_buy_quote, stocks_vault, stocks_create_vault, stocks_set_weights, stocks_buy, stocks_sell, stocks_rebalance, stocks_send (write tools return an unsigned transaction you sign yourself)
• Paid inside the tool call (x402 over MCP): polymarket_price_to_beat ($0.004), stocks_signals ($0.007). Call once without payment to get the x402 PaymentRequired, then call again with the signed payment in _meta["x402/payment"]; the data comes back with the receipt in _meta["x402/payment-response"] (x402 MCP transport spec). Pay on Base, Polygon or Arc.
• Paid prep (returns the HTTP 402 to pay yourself): polymarket_prepare ($0.004), stocks_signals_prepare ($0.007), stocks_publish_prepare ($0.01)
• Utilities: usdc_balances (every CCTP chain), cctp_status (any Circle CCTP transfer, and how to finish a stuck one), x402_check (decode a 402, verify a signed payment, get the fix), payment_readiness (can this wallet pay this endpoint)
• Other: gas_sponsor_info, liquid_guide

Plus 4 doc resources and 3 prompts (bridge USDC, earn referrals, buy the basket). Free to connect. Paid tools settle x402 inside the call; your agent signs with its own wallet. The server never signs or holds funds.

Discovery (machine-readable, self-hosted)

Agent skill (OpenClaw · ClawHub · skills.sh)

A ready-made skill that teaches an agent the whole flow lives in skills/liquid-agent-stocks/SKILL.md.

clawhub install liquid-agent-stocks          # OpenClaw / ClawHub — the stock index
clawhub install liquid-gas-sponsor           # OpenClaw / ClawHub — the gas sponsor (transact with USDC only, no ETH)
clawhub install liquid-polymarket            # OpenClaw / ClawHub: Polymarket official price to beat, live
npx skills add LiquidAgent/liquidagentx402   # skills.sh (any agent that reads SKILL.md): all four skills, incl. liquid-usdc-bridge and liquid-polymarket

Quickstart — create → buy → rebalance → exit

Reads are free. Writes return an unsigned {to,data,value,chainId} (or {steps:[...]}) that you sign and broadcast.

BASE=https://api.liquidagent.ai

# 1. Discover the index (free)
curl -s $BASE/v1/basket

# 2. Preview a $2 buy (free; USDC-6, so 2000000 = $2.00)
curl -s "$BASE/v1/quote?usdc=2000000"

# 3. Open your vault (ONE time) — returns an unsigned tx; sign + broadcast it
curl -s -X POST $BASE/v1/create-vault -H 'content-type: application/json' -d '{}'

# 4. Find your vault address
curl -s $BASE/v1/balance/0xYourAddress          # -> vaults[0].vault

# 5. (optional) Set custom weights — bps summing to 10000; sign + broadcast
curl -s -X POST $BASE/v1/set-weights -H 'content-type: application/json' \
  -d '{"vault":"0xYourVault","weightsBps":[4000,2000,2000,2000]}'

# 6. Buy in — ONE tx, no approve: get an EIP-2612 permit payload, sign it OFF-CHAIN,
#    then exchange the signature for a single unsigned depositWithPermit tx
curl -s -X POST $BASE/v1/buy -H 'content-type: application/json' \
  -d '{"vault":"0xYourVault","usdc":"2000000","permit":true,"owner":"0xYourAddress"}'
#    -> {typedData} ... sign with eth_signTypedData_v4, then:
curl -s -X POST $BASE/v1/buy -H 'content-type: application/json' \
  -d '{"vault":"0xYourVault","usdc":"2000000","permit":{"deadline":<from typedData>,"signature":"0x..."}}'
#    (omit `permit` entirely for the legacy approve + deposit two-step)

# 7. Check your vault (free)
curl -s $BASE/v1/vault/0xYourVault

# 8. (optional) Rebalance to target — sign + broadcast
curl -s -X POST $BASE/v1/rebalance -H 'content-type: application/json' -d '{"vault":"0xYourVault"}'

# 9. Cash out — to USDC or raw tokens; sign + broadcast
curl -s -X POST $BASE/v1/redeem -H 'content-type: application/json' \
  -d '{"vault":"0xYourVault","shares":"<amount>","inKind":false}'

Signing: every write returns an unsigned {to,data,value,chainId}. Sign it with your own wallet and broadcast via eth_sendRawTransaction to any Base RPC. deposit / rebalance / redeem swap B20 precompile tokens, which break naive public-RPC gas estimation — if estimation fails, pass an explicit gas limit of ~3,000,000.

Runnable examples: examples/buy.js (viem) · examples/buy.py (Python) · examples/read.sh (curl).

Endpoints

Reads (free): GET /v1/basket · GET /v1/vault/{address} · GET /v1/balance/{agent} · GET /v1/quote?usdc= · GET /v1/guide Writes (return unsigned calldata): POST /v1/create-vault · /v1/set-weights · /v1/buy · /v1/rebalance · /v1/redeem (sell / cash out) · /v1/send (transfer to any wallet) Paid (x402): GET /v1/signals ($0.007 — the basket's rebalancing signal in one call) · POST /v1/publish ($0.01 — a live, shareable portfolio page) · POST /v1/gas (from $0.03 — the gas sponsor: transact with USDC only, no ETH) · GET /v1/bridge (1% — the one-signature USDC bridge, Base <-> Arc)

An agent can buy the basket, sell it any block (/v1/redeem → USDC or the raw stocks in-kind), and send it to any wallet (/v1/send) — gift or hand a whole tokenized-stock basket to another agent in one transfer, no vault needed on their end.

Full spec in openapi.json.

Paid: basket signals (x402)

GET /v1/signals — $0.007 USDC per call — one call returns the whole basket's rebalancing signal, so an agent doesn't have to visit four sites: per-stock returns, annualized volatility, RSI, trend, relative strength, a correlation matrix, and an inverse-volatility suggested weightsBps you can drop straight into POST /v1/set-weights → POST /v1/rebalance. Add ?vault=<yours> to also get current-vs-suggested drift for your vault.

Pay by signing a USDC authorization (x402 exact scheme, EIP-3009, on Base) — any x402-aware client handles the 402 automatically:

curl -s https://api.liquidagent.ai/v1/signals            # -> 402 with the x402 payment challenge
# an x402 client (AgentCash, x402-fetch, CDP) pays the $0.007, then receives:
# { "basket":[{symbol,returns,volAnnualPct,rsi14,trend,relStrengthM1}, ...],
#   "basketStats":{ "correlation": {...} },
#   "signals":{ "riskParityWeightsBps":[...], "biasVsEqualWeightBps":[...], "momentumRankDesc":[...] } }

Everything else stays free; the paid resources are signals, publish, the gas sponsor, and the bridge below.

Paid: gas sponsor (x402) — transact with USDC only, no ETH

Most agent wallets hold USDC and nothing else. POST /v1/gas is an ERC-4337 paymaster you pay per operation in USDC over x402: no ETH, no account, no API key. Price is max($0.03, 1.3 × the operation's gas cap); the signed sponsorship locks the gas limits and max fee, so the sponsor can never charge more than it quoted. One endpoint, the body picks the lane:

Smart-wallet SDKs (ERC-7677). Point the SDK's paymaster URL at https://api.liquidagent.ai/v1/gas. pm_getPaymasterStubData is free; an unpaid pm_getPaymasterData returns a JSON-RPC error {code:402, data:<x402 PaymentRequired>} (HTTP stays 200 so SDKs don't choke). Put the x402 payment object in params[3].context.x402 and retry. Then send the signed operation back to the same URL, not to a public bundler: bundlers only relay staked paymasters and this one is not staked yet, so the bring-your-own-operation step below is the last mile (we dry-run and submit it ourselves).

Plain wallets (any EOA, via EIP-7702). Two calls to the same URL:

# 1. quote: the 402 IS the quote (exact price for THIS operation, valid 120 s)
curl -s -X POST https://api.liquidagent.ai/v1/gas -H 'content-type: application/json' \
  -d '{"sender":"0xYourEOA","calls":[{"to":"0x…","data":"0x…","value":"0"}]}'      # any calls, e.g. an unsigned tx from this API
# 2. pay it: an x402 client repeats the call with X-PAYMENT and receives
#    { userOperation (sponsored), typedData, authorization? (EIP-7702, only if your EOA is not delegated yet), validUntil }
#    sign typedData with eth_signTypedData_v4 (+ sign the authorization if given), then POST them back to the same URL:
#    {"userOperation": <with signature>, "authorization": <signed, optional>}  -> we submit; our deposit pays the gas.
#    No further charge. Only operations we sponsored are accepted, once each.

Full walkthrough with signatures in examples/gasless.js — a wallet with zero ETH buys the index end to end. Wallet already delegated to another EIP-7702 implementation (MetaMask and friends)? The first call returns 409; add "redelegate": true to the same body and the sponsor returns an authorization you sign that re-points the wallet to Simple7702Account (owner = you, reversible, applied in the same transaction), or keep your delegation and use the next section.

Any other smart account (bring your own operation). Already delegated to a different EIP-7702 implementation, or running a deployed smart account (Kernel, Safe, Nexus…) on EntryPoint v0.8? Build the operation with your own SDK and let the sponsor submit it — no bundler, no paymaster stake, no ETH:

# 1. quote: POST the UNSIGNED EntryPoint v0.8 operation (sender = your account, your calldata, your gas limits)
curl -s -X POST https://api.liquidagent.ai/v1/gas -H 'content-type: application/json' \
  -d '{"userOperation":{"sender":"0xYourAccount","nonce":"0x…","callData":"0x…","callGasLimit":"0x…","verificationGasLimit":"0x…","preVerificationGas":"0x…","maxFeePerGas":"0x…","maxPriorityFeePerGas":"0x…","signature":"0x"}}'
# 2. pay the 402 and repeat -> { userOperation (with the paymaster fields), typedData, validUntil }
# 3. sign it the way YOUR account expects (viem: account.signUserOperation), POST {"userOperation": <with signature>} to the same URL.
#    The sponsor dry-runs it through the EntryPoint first: a rejected dry run costs nothing and can be retried before validUntil.

Working reference in examples/gasless-bring-your-own.js: swap the account constructor for your SDK's. GET /v1/gas describes the sponsor; GET /v1/gas/stats shows live usage.

Paid: Polymarket price to beat (x402)

GET https://api.liquidagent.ai/v1/polymarket/<asset>-<timeframe> for BTC, ETH, SOL and XRP on 5m and 15m (e.g. btc-5m, eth-15m, sol-5m, xrp-15m), $0.004 USDC per call on Base or Polygon. Polymarket's public API only shows the price to beat after a window closes; this returns it live.

One call returns the official price to beat for the live window (the 60 s Chainlink TWAP before it starts, matched to every decimal against Polymarket's own published values on every resolved window tested), the live Chainlink price and its distance from the price to beat, seconds left, token ids and the market's prices. ?start=<unix> returns a past window's official settle and outcome. First call free: add ?free=1 for one live answer at no charge (one per agent). You are never charged when it cannot answer. Index: https://api.liquidagent.ai/v1/polymarket

Example: examples/polymarket.js. Skill: skills/liquid-polymarket/SKILL.md.

Liquid Bridge (x402): move USDC from Base to 16 chains in one signature

The one-signature USDC bridge for x402 agents. GET /v1/bridge?from=base&to=arc&amount=1 answers with a 402 that is the exact price. Sign one standard x402 payment, repeat the call, and exactly the amount you asked for arrives at your own address on the destination, usually in 10 to 20 seconds. No transaction to build, no approvals, no gas token. Non-custodial: the payment goes to the bridge contract, which burns it through Circle CCTP to you in the same transaction.

Price: 1% of the amount, plus Circle's network fee and gas at cost, all in the quote. Minimum 1 USDC. Liquid's fee can never exceed max(3%, $0.05): the contract enforces it.

Earn by referring: add ref=<your address> to any bridge URL. 20% of Liquid's fee is credited to you on-chain in the same transaction (self-referral works as a 20% discount). Check it at GET /v1/bridge/earnings/<address>.

node examples/bridge.js --quote                                      # free price check
PRIVATE_KEY=0x... node examples/bridge.js --from base --to arc --amount 1 [--ref 0xYourReferrer]

Free: GET /v1/bridge/quote · /v1/bridge/routes · /v1/bridge/status/{burnTx} · /v1/bridge/earnings/{referrer} · /v1/bridge/guide. Skill: skills/liquid-usdc-bridge/SKILL.md. Full guide: https://api.liquidagent.ai/v1/bridge/guide

Addresses — Base mainnet (chainId 8453)

Fees & mechanics

• 0.20% mint fee on deposits · 0.90%/yr streaming management fee · no performance fee. Both hard-capped in bytecode.
• Self-priced NAV from a pool TWAP with a spot-vs-TWAP circuit breaker that fails closed. No external oracle.
• Band-rebalanced at a 5% drift band + 1h cooldown; a 5% USDC buffer smooths flows.
• In-kind redemption is price-free and can never be paused — you're never trapped.
• No project token in the live index. (A LIQUID revenue-share token is on the later roadmap; the Phase 1 index itself has none.)

License

MIT — see LICENSE.