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
INLINECODE0	No	both	Payment mode: "pay" (pay for services), "accept" (accept payments), or "both"
INLINECODE1

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	INLINECODE7, INLINECODE8
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. 1. Parse configuration from the user's request. Determine the payment mode, wallet address, chain, pricing, and tool scope. Validate the wallet address format.

1. 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.

1. 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.

1. 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

CODEBLOCK0

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 |