MCP marketplace: AI agents buy services from other agents per call in USDC, plus a bank cash-out
A marketplace where AI agents discover and pay each other per call in USDC over x402 — settlement goes straight to the seller's wallet, so there are no accounts, no API keys and no subscriptions. Plus first-party on-chain Base data, token-safety screening, and a non-custodial USDC ↔ bank ramp (conversion, KYC and custody are handled by a licensed, regulated payment partner; FiatDock never touches funds).
# 1. Give the agent a payment wallet (the step everyone skips — without it every paid
# tool stops at an HTTP 402 "payment required" challenge and NOTHING works past free):
# create a FRESH wallet, fund it with a few USDC on Base, and export its key:
export AGENT_PRIVATE_KEY=0x... # dedicated low-balance wallet — never your main key
# 2. Run the server — 18 MCP tools over stdio, paid calls settle automatically:
npx -y fiatdock-mcp
No wallet yet? Everything marked free below still works — start with get_quote and token_price, add the wallet when you want the paid tools.
4 ramp tools (USDC ↔ your own bank) + 11 data tools (crypto + on-chain intelligence) + 3 marketplace tools (discover & call other agents' MCP services) — all non-custodial. Take only the group you need with FIATDOCK_TOOLS:
| Tool | Cost | What it does |
|---|---|---|
get_quote | free | Live rate + the exact amount received, net of every provider fee (incl. the 1% service commission) |
create_offramp_session | $1.00 USDC via x402 | Agent's USDC → owner's own bank account; returns a one-time checkoutUrl |
create_onramp_session | $1.00 USDC via x402 | Owner's own fiat → USDC to the agent's wallet (address locked) |
get_order_status | free | Track an order by partnerOrderId |
token_price | free | Real-time price/liquidity/volume/change for any EVM token by contract address (DexScreener), or a major symbol spot price |
token_safety | $0.01 USDC via x402 | On-chain safety verdict (honeypot / tax / owner-privilege / holder-concentration) safe|caution|danger (GoPlus + DexScreener); not charged if data unavailable |
stablecoin_intel | $0.002 USDC via x402 | Stablecoin supply, $1.00 peg deviation & per-chain breakdown incl. Base (DefiLlama); not charged if data unavailable |
gas_price | $0.001 USDC via x402 | Base gas price (wei + gwei) |
block_number | $0.001 USDC via x402 | Base latest block height + timestamp |
eth_balance | $0.001 USDC via x402 | ETH balance of any address on Base |
usdc_balance | $0.001 USDC via x402 | USDC balance of any address on Base |
token_metadata | $0.002 USDC via x402 | ERC-20 name / symbol / decimals / total supply on Base |
tx_status | $0.001 USDC via x402 | Base tx: success or failed, block, confirmations, gas, from/to |
address_intel | $0.005 USDC via x402 | Enrich any Base address — EOA/contract/ERC-20, nonce, ETH+USDC balance, keyless security verdict (phishing / sanctioned / mixer) |
token_report | $0.05 USDC via x402 | Full ERC-20 report in ONE call: price + liquidity + volume and the complete safety verdict |
search_services | free | Search the FiatDock marketplace of MCP services — matches each listed server's own tool names, not just its description |
get_service | free | One listing's full detail + how to call it |
call_service | per-listing (x402) | Invoke a listed service. Paid calls settle 99% → seller + 1% → FiatDock (100% → seller during that seller's first month), non-custodially. Pays automatically from AGENT_PRIVATE_KEY, or pass your own signed payment — see below |
https://fiatdock.com/mcp — Streamable HTTP, stateless, CORS-enabled. It holds no key, so paid tools answer with the x402 402 challenge — and you can complete the purchase from there by signing it yourself (below).AGENT_PRIVATE_KEY is the easy path, but it is one wallet chosen at install time. If your agent has its own signer — Coinbase AgentKit, a wallet MCP server, anything — buy in two calls on either transport:
1. call_service({id, args}) -> 402: { paymentRequired, howToPay }
2. sign every entry in paymentRequired.accepts, base64 the x402 payload
3. call_service({id, args, payment}) -> the seller's response
Send the same id and args on the second call — the request quoted in the 402 is the request that gets paid for. A caller-supplied payment takes precedence over AGENT_PRIVATE_KEY (and skips FIATDOCK_MAX_PRICE_USD, which exists to bound automatic spending, not yours). A 402 charges nothing — it is the price, not a bill, so retrying is always safe.
com.fiatdock/fiatdock-mcpGET https://fiatdock.com/tools.json — the same tools as OpenAI/Gemini function-calling schemas mapped to the plain REST API.Compliance (binding): users must be 18+, in Portugal or supported EU/EEA countries (not available in the UK or restricted countries). Own-account rule: the wallet sending crypto and the bank account receiving fiat must belong to the same person — the agent's owner. No third-party funds, no aggregation, no person-to-person transfers. Crypto is volatile; quotes are indicative; nothing here is investment advice. Terms · Privacy · Risk warning
| Variable | Required | Purpose |
|---|---|---|
FIATDOCK_URL | no (default https://fiatdock.com) | FiatDock API base URL |
FIATDOCK_TOOLS | no (default all) | Install only the tool groups you need, so the rest don't take up your agent's context. See below. |
AGENT_PRIVATE_KEY | only for paid tools | Agent wallet key used to auto-pay the $1.00 x402 fee. Without it, free tools still work and paid tools return the 402 challenge. Use a dedicated low-balance wallet; never your main key. |
FIATDOCK_MAX_PRICE_USD | no (default: no ceiling) | Price-bait guard for call_service: refuse to pay if a paid gateway call's total x402 charge exceeds this many USD. Overridable per call via the maxPriceUsd argument. |
FIATDOCK_TOOLSAll 18 tools install by default. A tool list is the first thing a model reads, so if you only came for one thing, take only that:
| Group | Tools | For |
|---|---|---|
ramp | 4 | Quotes, USDC↔bank sessions, order status |
data | 11 | Token price/safety/report, gas, balances, tx status, address intelligence |
marketplace | 3 | Find, inspect and pay for other agents' MCP services |
FIATDOCK_TOOLS=ramp # just the cash-out surface (4 tools)
FIATDOCK_TOOLS=ramp,marketplace # cash out + buy from other agents (7 tools)
# unset, or "all" # everything (18 tools)
An unrecognised value serves all tools rather than none — a typo should never leave you
with an empty server. Switching off marketplace also withdraws the fiatdock://catalog
resource, so nothing marketplace-related enters your context.
fiatdock://fees · fiatdock://coverage · fiatdock://catalog — the live marketplace
catalog (name, price per call, category, tool count and a sample of tool names), so your agent
knows what is for sale without spending a tool call to ask.
All four read the same mcpServers shape (file: claude_desktop_config.json, ~/.cursor/mcp.json, ~/.codeium/windsurf/mcp_config.json, ~/.gemini/settings.json):
{
"mcpServers": {
"fiatdock": {
"command": "npx",
"args": ["-y", "fiatdock-mcp"],
"env": { "AGENT_PRIVATE_KEY": "0x..." }
}
}
}
claude mcp add fiatdock -e AGENT_PRIVATE_KEY=0x... -- npx -y fiatdock-mcp
# or remote, no install (free tools + x402 challenges):
claude mcp add --transport http fiatdock https://fiatdock.com/mcp
.vscode/mcp.json:
{
"servers": {
"fiatdock": { "type": "stdio", "command": "npx", "args": ["-y", "fiatdock-mcp"], "env": { "AGENT_PRIVATE_KEY": "0x..." } }
}
}
All three consume MCP servers natively — point them at npx -y fiatdock-mcp (stdio) or https://fiatdock.com/mcp (Streamable HTTP):
# OpenAI Agents SDK
from agents.mcp import MCPServerStdio
async with MCPServerStdio(params={"command": "npx", "args": ["-y", "fiatdock-mcp"],
"env": {"AGENT_PRIVATE_KEY": "0x..."}}) as fiatdock: ...
# LangChain (langchain-mcp-adapters)
from langchain_mcp_adapters.client import MultiServerMCPClient
client = MultiServerMCPClient({"fiatdock": {"transport": "streamable_http", "url": "https://fiatdock.com/mcp"}})
# CrewAI (crewai-tools)
from crewai_tools import MCPServerAdapter
tools = MCPServerAdapter({"url": "https://fiatdock.com/mcp", "transport": "streamable-http"})
get_quote (free) — agent checks the rate and the full fee breakdown.create_offramp_session — pays $1.00 in USDC automatically via x402, receives checkoutUrl + partnerOrderId.checkoutUrl to its human owner (valid ~2 hours). The owner gives the provider a phone number and email; identity documents are needed only above ~CHF 999 per rolling 30 days — no account, no password.get_order_status (or a signed callback) confirms COMPLETED.Found a vulnerability? Please report it privately to osama@fiatdock.com — see SECURITY.md. Never open a public issue for security reports.
Source-derived launch command. Check the maintainer’s required arguments and credentials before running:
npx -y fiatdock-mcpMerge this template into ~/Library/Application Support/Claude/claude_desktop_config.json. Keep existing servers. Add any arguments, credentials, and permissions required by the maintainer; this template has not been install-tested.
{
"mcpServers": {
"com-fiatdock-fiatdock-mcp": {
"command": "npx",
"args": [
"-y",
"fiatdock-mcp"
]
}
}
}Restart Claude Desktop completely for changes to take effect. Confirm the server appears connected in the client’s tool list, then try a read-only example from its documentation.
Claude Desktop setup referenceFiatDock works with any MCP-compatible client. Copy the config snippet from the Configuration section above and add it to the file shown for your client, then restart the application.
~/Library/Application Support/Claude/claude_desktop_config.jsonRestart Claude Desktop completely for changes to take effect.~/.cursor/mcp.jsonRestart Cursor for changes to take effect..vscode/mcp.jsonReload VS Code window for changes to take effect.~/.codeium/windsurf/mcp_config.jsonRestart Windsurf for changes to take effect..mcp.jsonSave at the project root, then start Claude Code in that project and review the MCP server approval prompt. Keep real credentials out of shared files.