com.deepfirstsearch/agent-pay-mcp

Deep First Search: safe x402 payments for AI agents

Safe rails for the agent economy. Search deep. Reveal only what you choose.

AI agents now pay for things over x402. Every one of those payments is public, and any agent can be talked into paying the wrong party. Deep First Search makes the model propose payments while the owner's signed policy decides.

Try it in 10 seconds

No keys, no wallet, no chain: a local x402 merchant plays honest and hostile, and you watch the agent pay for data and refuse four attacks.

npx @deepfirstsearch/agent-pay demo

Pick your path

You use	Install	Guide
Claude Desktop, Claude Code, Cursor, any MCP client	npx @deepfirstsearch/agent-pay-mcp	integrations/mcp
Vercel AI SDK	npm i @deepfirstsearch/agent-pay-ai-sdk	integrations/ai-sdk
LangChain.js / LangGraph	npm i @deepfirstsearch/agent-pay-langchain	integrations/langchain
Your own agent, any wallet	npm i @deepfirstsearch/agent-pay	sdk
On-chain budgets on Base	npx @deepfirstsearch/agent-pay owner help	owner CLI

Full developer guide: deepfirstsearch.com/developers · building a wallet, framework or platform? Partners.

What's in this repository

Component	What it does	Status
MCP server (integrations/mcp/)	Model Context Protocol server: Claude Desktop, Claude Code, Cursor and any MCP client get paid_fetch, list_merchants and budget_status tools that pay x402 APIs inside the owner's budget	✅ npx @deepfirstsearch/agent-pay-mcp · tested with a real Claude session on Base Sepolia
Agent Safe (contracts/)	On-chain vault: owner-signed, timelocked, per-merchant budgets; the agent key can spend but never widen	✅ 98 tests (fuzzing, invariants, properties, regressions, Base mainnet fork with real USDC), two internal reviews · live on Base mainnet (beta)
agent-pay SDK (sdk/)	x402 v2 client with a policy engine outside the model, prompt-injection guards, per-merchant payers, owner CLI	✅ 162 tests incl. on-chain loops and the official x402 facilitator · npx @deepfirstsearch/agent-pay owner …
Framework tools (integrations/)	Vercel AI SDK paidFetchTool, LangChain/LangGraph createPaidFetchTool	✅ on npm
$DEPTH (contracts/)	1B fixed supply, no mint function, no owner; fees burned through a fee jar + firepit	✅ Implemented · not launched
Website (web/)	Site, whitepaper, tokenomics, partner kit, legal pages; strict CSP, zero third parties	✅

MCP server: let Claude or Cursor pay x402 APIs safely

@deepfirstsearch/agent-pay-mcp is a stdio MCP server. The model gets three tools and nothing that can move money on its own terms:

MCP tool	What it does
paid_fetch(url, method?, body?, contentType?)	Fetches a URL; if it answers 402 Payment Required, pays in USDC on Base only when the merchant, price and budget match your config
list_merchants()	Merchants the agent may pay, their prices and the remaining budget
budget_status()	Remaining budget per merchant, plan window, vault balance

{ "mcpServers": { "agent-pay": {
    "command": "npx", "args": ["-y", "@deepfirstsearch/agent-pay-mcp", "/path/config.json"],
    "env": { "AGENT_PAY_AGENT_KEY": "0x…", "AGENT_PAY_BURNER_SEED": "0x…" } } } }

Payees, prices and limits come from the config file and the owner-signed on-chain budget, never from the model or a 402 response, so a prompt-injected agent can't overspend or pay an attacker. Setup, config reference and a 5-minute Base Sepolia demo: integrations/mcp.

Status: pre-launch. Live on Base Sepolia, with a real x402 payment settled (see deployments); unaudited beta on Base mainnet since 2026-10-06 (small amounts, our own funds first, then invited design partners) while we arrange an independent audit; the public launch comes after the audit. No token exists.

Develop on this repository

# Contracts (needs Foundry: curl -L https://foundry.paradigm.xyz | bash && foundryup)
git submodule update --init --recursive
cd contracts && forge test

# SDK
cd ../sdk && npm ci && npm test && npm run demo

# Website
cd ../web && npm ci && npm run dev

Documents

Whitepaper	Formal design, privacy model, risks (EN; structured for MiCA Annex I)
Tokenomics	Supply, allocation, Firepit burn, vesting (EN)
Decisions	ADRs: ticker, chain, burn, vesting, stand… (ES)
Deployments	Base Sepolia contract addresses and the live demo vault
Audit scope	Scope, nSLOC, roles, known issues and questions for reviewers
Airdrop tool	Builds the airdrop Merkle tree and proofs; tested against the contract
Mainnet runbook	Safes, rehearsal, deploy, checks, guarded launch, monitoring
Security assessment	Pentest findings, threat model, evidence (ES)
Research	Market pain, successes, failures, token models, launch mechanics (ES)

Key decisions

• Ticker: $DEPTH.
• Chain: Base.
• Founder: 12%, nothing for 12 months, then 36 months linear, on-chain; the vesting contract cannot be transferred and the beneficiary is a public Safe.
• Burn: burn-to-claim fee jar (no swaps, oracles or admins), fed only by Agent Safe, SDK and inference fees, never by privacy-pool fees.
• No conference booth until there are users; hackathons instead.
• No own privacy pool: integrate a third-party compliant one (ADR-011). Sales geo-blocked for the US and Argentina (ADR-012).

Security

See SECURITY.md to report vulnerabilities.

Contact

Built by Nicolas Tursi. General contact: hello@deepfirstsearch.com. Security reports: see SECURITY.md or write to security@deepfirstsearch.com.

License

MIT (contracts and SDK).