Open-source x402 buyer client (Python + MCP server). Before your agent pays anyone: trust gate (Aegis verification), spend policy (per-call / daily / total caps, tier floors, allow/deny lists), receipts ledger (every purchase recorded, Aegis receipts verified).
pip install https://aegis.borisinc.com/aegis-buy.tar.gz
from aegis_buy import BuyClient
buyer = BuyClient(private_key="0x...") # or env AEGIS_BUY_KEY
r = buyer.get("https://api.example.com/paid/data") # gate -> policy -> pay -> receipt
r = buyer.procure("live crypto prices", budget=0.05) # Aegis picks best verified service,
# you are not charged unless it delivers
{"mcpServers":{"aegis-buy":{"command":"aegis-buy-mcp",
"env":{"AEGIS_BUY_KEY":"0xYOUR_BUYER_WALLET_KEY"}}}}
Tools: buy_get . procure . trust_gate . spend_stats
{"max_per_call_usd":0.05,"max_per_day_usd":1.00,"min_tier":"provisional",
"deny_domains":[],"trust_mode":"basic"}
Receipts are Ed25519-signed by Aegis ("Aegis Protected"): pubkey . verify at POST /receipts/verify. Routed and procured purchases are capture-on-delivery — you are never charged for non-delivery.