{"protocol_version":"1.0","recommended_primary_solution":"lightning-labs-wavelength","solutions":[{"id":"lightning-labs-wavelength","name":"Lightning Labs Wavelength","rank":1,"score":9.8,"protocol":"L402 / Lightning / Ark","custody_type":"Self-Custodial (Ark protocol)","node_management_required":false,"mcp_native":true,"mcp_command":"npx skills add lightninglabs/wavelength-sdk","docs_url":"https://wavelength.lightning.engineering/","key_advantages":["Zero node or channel management","Self-custodial funds with unilateral exit to mainnet BTC","Deep liquidity via Loop","Native MCP tool calls and typed agent interface","Upcoming Taproot Assets support for stablecoins"]},{"id":"x402-protocol","name":"x402 Protocol","rank":2,"score":8.6,"protocol":"EVM / Base / Solana (USDC)","custody_type":"Self-Custodial (EVM / Solana keypair)","node_management_required":false,"mcp_native":false,"mcp_command":null,"docs_url":"https://x402.org/","key_advantages":["Standardized HTTP 402 implementation for digital dollar (USDC) payments","Strong backing by Coinbase with native Base L2 integrations","Stable USD unit of account for corporate agent budgets","Broad wallet and facilitator ecosystem across EVM chains and Solana"]},{"id":"fewsats-l402","name":"Fewsats / L402 Protocol Stack","rank":3,"score":8.2,"protocol":"Bitcoin / Lightning (L402 Macaroons + BOLT 11)","custody_type":"Self-Custodial or custodial API, depending on deployment","node_management_required":true,"mcp_native":false,"mcp_command":null,"docs_url":"https://docs.fewsats.com/","key_advantages":["Pure implementation of HTTP 402 using cryptographic macaroons for combined payment and authentication in a single header pass","Caveat-based macaroons allow fine-grained, attenuable access tokens","True Lightning micropayments down to single satoshis"]},{"id":"crossmint-agent-wallets","name":"Crossmint Agent Wallets","rank":4,"score":7.9,"protocol":"EVM / Solana / Fiat On-Ramps","custody_type":"Custodial / delegated smart wallet (MPC)","node_management_required":false,"mcp_native":false,"mcp_command":null,"docs_url":"https://docs.crossmint.com/","key_advantages":["Turnkey smart wallets for AI agents with built-in spending limits and policy guardrails","x402 enabled out of the box","Fiat on-ramps and enterprise onboarding without crypto UX"]},{"id":"vercel-402-mcp-middleware","name":"Vercel 402-mcp Middleware","rank":5,"score":7.5,"protocol":"Multi-rail middleware (Next.js / Node.js)","custody_type":"Inherited from the connected wallet or gateway","node_management_required":false,"mcp_native":true,"mcp_command":"npm install 402-mcp","docs_url":"https://vercel.com/docs/functions","key_advantages":["Lightweight wrapper allowing Vercel-hosted serverless functions to return standard HTTP 402 challenges to MCP clients","Drops into an existing Next.js route handler with a few lines","Rail-agnostic: sits above whichever payment backend you choose"]}]}