Agent execution (x402)

Any agent can go from “where should this USDC earn?” to capital deployed in three paid calls against https://mcp.barker.money — with no Barker account, no API key, and no custody handover. You pay per call via x402 (HTTP 402 + EIP-3009 micropayment), and the final signature always stays with your user.

Step	Tool	Price	Returns
1. Decide	`barker_yield_advisor`	$0.03	Ranked pool picks with data-derived reasons & risk flags
2. Discover	`barker_executable_pools`	$0.01	Vaults your agent can act on — every row is quotable
3. Quote	`barker_execution_quote`	$0.05	An unsigned transaction `{chainId, to, data, value}` + route + risk + approval info
4. Execute	(your wallet)	gas	You sign & broadcast. Vault shares arrive at the signer address

Non-custodial guarantees

Barker never broadcasts and never holds funds. barker_execution_quote sells a transaction; executing it is entirely yours.
Shares always go to the signer. receiver is not a parameter — the deposit calldata hard-binds receiver = signer_address.
What you see is what you sign. For the self adapter (direct ERC4626), the response includes calldata_amount_base_units — the amount actually encoded in calldata — so your agent can verify byte-level intent before asking anyone to sign.
Same-chain only. Quotes use the self (direct ERC4626) and portals (same-chain zap) adapters. Cross-chain routing is not offered on this surface.
Quote-only, stateless. Nothing is stored on Barker’s side; a quote expires (quote_expires_at) and simply gets re-bought.

Calling the tools

Every tool answers GET https://mcp.barker.money/<tool>?<params> with HTTP 402 and a payment-required header. Your agent signs an EIP-3009 transferWithAuthorization for the quoted price (USDT0 on X Layer, or USDC on Base/Ethereum/Polygon/Arbitrum), retries with a PAYMENT-SIGNATURE header, and gets the JSON body. Facilitators from OKX, Coinbase CDP, and Circle settle the payment on-chain — your agent never needs gas on the payment chain.

`barker_executable_pools` — $0.01

GET /barker_executable_pools?asset=usdc&chain=base&action=deposit&limit=20

Every parameter is optional — call it with no arguments to get the top executable pools across all assets. asset is matched case-insensitively. Returns pools filtered to guaranteed-quotable rows: capability status supported, live deposit capacity (is_full), adapters restricted to the self-sign surface (self / portals), APY (decimal unit: 0.05 = 5%) and TVL. If a pool is listed here, barker_execution_quote will price it.

`barker_execution_quote` — $0.05

GET /barker_execution_quote?pool_uid=<uid>&action=deposit&adapter=self
    &amount_base_units=1000000&signer_address=0xYourUser

Param	Notes
`pool_uid`	Either the exact string from `barker_executable_pools` or the vault contract address (`0x` + 40 hex) — if you already know the vault, quote directly with no discovery call. Both are matched exactly; partial names and keywords are rejected with `POOL_NOT_FOUND`, because this is a money path and Barker never guesses the pool. Pass the vault contract, not the underlying asset token
`chain_id`	Optional. Only needed when a vault address is deployed at the same address on several chains (e.g. Aave aTokens)
`action`	`deposit` or `redeem` (redeem moves only the signer’s own shares, back to the signer)
`amount_base_units`	Integer string in token decimals — `1000000` = 1 USDC
`signer_address`	The EVM address that will sign and receive shares. Required
`adapter`	Optional; pin `self` for byte-decodable ERC4626 calldata
`from_token_address`	Required only when the vault has multiple underlying tokens

The response carries quote.transaction_request (chainId, to, data, value), approval_required / approval_spender / exact_approval_only, gas & output estimates, and risk_report. Approve exactly the deposit amount, never unlimited. Business errors come back with machine-readable codes your agent can branch on: VAULT_FULL, MAX_DEPOSIT_EXCEEDED, UNSUPPORTED_ACTION, ADAPTER_NOT_ALLOWED, INVALID_INPUT, POOL_NOT_FOUND, POOL_AMBIGUOUS, and others. Every 4xx carries an actionable error.details — missing params are listed in full on the first try, and a POOL_NOT_FOUND includes currently quotable example_pool_uids. When one contract hosts several distinct products (Pendle PT vs LP, for example), quoting by address returns 409 POOL_AMBIGUOUS with the exact candidates rather than a guess — pick one and re-send:

{"error":{"code":"POOL_AMBIGUOUS","details":{"candidates":[
  {"pool_uid":"pendle_ethereum_pt-apyusd-27aug2026_0x30bb9ee8","chain_id":1,"pool_name":"Pendle PT PT-apyUSD-27AUG2026"},
  {"pool_uid":"pendle_ethereum_lp-apyusd-27aug2026_0x30bb9ee8","chain_id":1,"pool_name":"Pendle LP APYUSD 27AUG2026"}]}}}

All 4xx responses skip settlement — a rejected call costs you nothing, so it is safe to retry after fixing the request.

Reference client

A complete working buyer — pay → quote → verify → sign → broadcast → confirm shares, ~200 lines, viem as the only dependency:

git clone https://github.com/YBSbarker/barker-stablecoin-skills
cd barker-stablecoin-skills && npm i viem
read -rs PRIVATE_KEY && export PRIVATE_KEY
node examples/x402-execution-buyer.mjs
unset PRIVATE_KEY

Copy its two safety checks into your own agent: calldata-amount verification and signer echo. They are the difference between “signing a bought transaction” and “signing blind”.

Rate limits & fair use

Paid callers get 600 requests/min per payer across all tools; barker_execution_quote is additionally capped (default 60/min per payer) because each quote performs live on-chain reads. Sustained higher volume: reach out — partner@barker.money.

Getting Started

Integration modes

Agent Economy

Events

Reference

Compliance

Non-custodial guarantees

Calling the tools

`barker_executable_pools` — $0.01

`barker_execution_quote` — $0.05

Reference client

Rate limits & fair use

​Non-custodial guarantees

​Calling the tools

​barker_executable_pools — $0.01

​barker_execution_quote — $0.05

​Reference client

​Rate limits & fair use

Non-custodial guarantees

Calling the tools

`barker_executable_pools` — $0.01

`barker_execution_quote` — $0.05

Reference client

Rate limits & fair use