Configure x402

Overview

Configures the x402 HTTP-native payment protocol for agent-to-agent micropayments settled on Base. x402 uses the HTTP 402 "Payment Required" status code to enable pay-per-request billing — agents pay fractions of a cent per API call in USDC, with ~200ms settlement, no API keys, no accounts, and no subscriptions.

This skill supports two modes:

• Pay mode: Configure your agent to pay for MCP tool calls and external API access via x402
• Accept mode: Configure your agent as an x402 service provider that accepts micropayments for its services
• Both: Enable bidirectional x402 payments

x402 has processed 100M+ agent-to-agent transactions across 80+ ecosystem projects (Feb 2026). It eliminates API key onboarding friction and creates revenue streams from every agent interaction.

When to Use

Activate when the user says:

• "Set up x402 payments for my agent"
• "Enable pay-per-swap via x402"
• "Configure my agent to accept x402 payments"
• "Set up micropayments on Base"
• "Enable x402 for my MCP server"
• "Monetize my agent's API"
• "Configure pay-per-request billing"
• "Set up agent-to-agent payments"

Parameters

Parameter	Required	Default	Description
mode	No	both	Payment mode: "pay" (pay for services), "accept" (accept payments), or "both"
walletAddress	Yes	--	USDC wallet address on Base for sending/receiving payments
chain	No	base	Settlement chain (Base recommended for ~200ms settlement)
pricePerCall	No	see pricing	Price per MCP tool call in USDC (for accept mode). Defaults to recommended pricing below.
supportedTools	No	all	Which MCP tools to gate behind x402 payments (for accept mode). "all" or comma-separated list.
maxSpendPerHour	No	$1.00	Maximum x402 spend per hour (for pay mode). Safety limit to prevent runaway costs.
facilitator	No	auto	x402 facilitator to use. "auto" selects the best available facilitator on Base.

Recommended Pricing (Accept Mode)

Tool Category	Price per Call	Examples
Price quotes	$0.001	get_token_price, get_quote
Pool analytics	$0.003	get_pool_info, get_pool_volume_history
Route optimization	$0.005	get_pools_by_token_pair, search_tokens
Simulation	$0.01	simulate_transaction
Execution	$0.05	execute_swap, add_liquidity

Workflow

1. Parse configuration from the user's request. Determine the payment mode, wallet address, chain, pricing, and tool scope. Validate the wallet address format.

2. Validate wallet: Verify the wallet address exists on the target chain and has a USDC balance (for pay mode) or can receive USDC (for accept mode). Check that the chain supports x402 settlement.

3. Write x402 configuration: Generate the x402 configuration file at .uniswap/x402-config.json with:

   • Payment mode (pay/accept/both)
   • Wallet address and chain
   • Facilitator endpoint
   • Per-tool pricing (accept mode)
   • Spending limits (pay mode)
   • Supported tools list

   For accept mode, also generate the .well-known/x402-manifest.json that advertises the agent's x402-enabled endpoints to other agents.

4. Verify setup: Confirm the configuration is valid by checking:

   • Wallet connectivity on the settlement chain
   • Facilitator availability
   • USDC token approval for the facilitator contract (if pay mode)
   • Configuration file is properly formatted

Output Format

x402 Configuration Complete

  Mode:         Both (pay + accept)
  Chain:        Base (8453)
  Wallet:       0x1234...abcd
  Facilitator:  Auto-selected (Coinbase x402)

  Pay Mode:
    Max Spend:  $1.00/hour
    USDC Balance: $50.00 (sufficient)

  Accept Mode:
    Pricing:
      Price quotes:       $0.001/call
      Pool analytics:     $0.003/call
      Route optimization: $0.005/call
      Simulation:         $0.010/call
      Execution:          $0.050/call
    Tools Gated:  All (17 tools)

  Config Files:
    .uniswap/x402-config.json
    .well-known/x402-manifest.json

  Status: Ready for x402 payments

Important Notes

• x402 settles on Base by default (~200ms). Ethereum mainnet settlement is possible but slower and more expensive.
• USDC is the only supported payment token for x402. The wallet must hold USDC on the settlement chain.
• The maxSpendPerHour safety limit prevents runaway costs in pay mode. Adjust based on expected usage.
• x402 uses the HTTP 402 "Payment Required" status code. When a client hits an x402-gated endpoint without payment, it receives a 402 response with payment instructions.
• Facilitators handle the payment settlement. The "auto" option selects the best available facilitator on the target chain.
• For accept mode, the .well-known/x402-manifest.json file makes your agent discoverable on Coinbase Bazaar (12,365+ services).
• x402 payments are per-request. There are no subscriptions, API keys, or accounts. Each request includes a micropayment.
• All x402 transactions are logged for treasury management and can be tracked via the manage-treasury skill.
• This skill does not execute any on-chain transactions. It only generates configuration files. The actual x402 payment flow happens at runtime when the MCP server processes requests.

Error Handling

Error	User-Facing Message	Suggested Action
Invalid wallet	"Invalid wallet address format."	Provide a valid Ethereum address (0x...)
No USDC balance	"Wallet has no USDC on [chain]. x402 payments require USDC."	Fund the wallet with USDC on Base
Chain not supported	"[chain] does not support x402 settlement."	Use Base (recommended) or Ethereum
Facilitator unavailable	"No x402 facilitator available on [chain]."	Try Base (most facilitators available)
Config write failed	"Could not write x402 configuration: [reason]."	Check file permissions
Wallet not configured	"No agent wallet found. Set up a wallet first."	Use setup-agent-wallet skill first
Invalid pricing	"Price per call must be positive and in USDC."	Provide valid pricing values