LDK MCP Server

Instructions

Implementation Reference

• src/tools/generateInvoice.ts:29-182 (handler)

  The execute handler function that implements the core logic: converts amount to millisatoshis, generates invoice via LightningService, formats response with success details and SwiftUI example code.

    execute: async (args: any): Promise<ToolResult> => {
      try {
        const amountMsat = args.amountSats * 1000;
        const invoice = await lightningService.generateInvoice(
          amountMsat,
          args.description,
          args.expirySeconds || 3600
        );
  
        return {
          content: [{
            type: 'text',
            text: JSON.stringify({
              success: true,
              invoice: invoice.bolt11,
              paymentHash: invoice.paymentHash,
              amountSats: args.amountSats,
              expiryTime: invoice.expiryTime,
              description: invoice.description,
              swiftExample: `
  // Swift code to generate and display Lightning invoice using LDK
  import SwiftUI
  import LightningDevKit
  import CoreImage.CIFilterBuiltins
  
  class InvoiceGenerator {
      let channelManager: Bindings.ChannelManager
      let logger: Bindings.Logger
      let keys: Bindings.KeysManager
      
      init(channelManager: Bindings.ChannelManager, logger: Bindings.Logger, keys: Bindings.KeysManager) {
          self.channelManager = channelManager
          self.logger = logger
          self.keys = keys
      }
      
      func createInvoice(amountMsat: UInt64?, description: String, expirySecs: UInt32 = 3600) -> Result<Bindings.Bolt11Invoice, Error> {
          let invoiceParams = Bindings.InvoiceBuilder.newInvoiceBuilder()
          
          if let amount = amountMsat {
              invoiceParams.amountMsat(amount)
          }
          
          invoiceParams.description(description.asLdkStr())
          invoiceParams.expiryTime(expirySecs)
          
          do {
              let invoice = try invoiceParams.build()
              return .success(invoice)
          } catch {
              return .failure(error)
          }
      }
  }
  
  struct InvoiceView: View {
      let invoice = "${invoice.bolt11}"
      let amountSats = ${args.amountSats}
      @State private var isCopied = false
      
      var body: some View {
          VStack(spacing: 20) {
              Text("Lightning Invoice")
                  .font(.title)
              
              // QR Code
              Image(uiImage: generateQRCode(from: invoice))
                  .interpolation(.none)
                  .resizable()
                  .scaledToFit()
                  .frame(width: 250, height: 250)
                  .overlay(
                      RoundedRectangle(cornerRadius: 16)
                          .stroke(Color.secondary.opacity(0.3), lineWidth: 1)
                  )
              
              // Amount
              VStack(spacing: 4) {
                  Text("\\(amountSats)")
                      .font(.system(size: 36, weight: .bold, design: .rounded))
                  Text("sats")
                      .font(.subheadline)
                      .foregroundColor(.secondary)
              }
              
              // Invoice details
              Text("${args.description || 'Lightning Payment'}")
                  .font(.subheadline)
                  .foregroundColor(.secondary)
                  .multilineTextAlignment(.center)
              
              // Copy button with feedback
              Button(action: {
                  UIPasteboard.general.string = invoice
                  withAnimation(.easeInOut(duration: 0.2)) {
                      isCopied = true
                  }
                  DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
                      withAnimation(.easeInOut(duration: 0.2)) {
                          isCopied = false
                      }
                  }
              }) {
                  Label(
                      isCopied ? "Copied!" : "Copy Invoice",
                      systemImage: isCopied ? "checkmark.circle.fill" : "doc.on.doc"
                  )
                  .frame(minWidth: 150)
              }
              .buttonStyle(.borderedProminent)
              .tint(isCopied ? .green : .accentColor)
              
              // Share button
              ShareLink(item: invoice) {
                  Label("Share", systemImage: "square.and.arrow.up")
              }
              .buttonStyle(.bordered)
          }
          .padding()
      }
      
      func generateQRCode(from string: String) -> UIImage {
          let context = CIContext()
          let filter = CIFilter.qrCodeGenerator()
          filter.message = Data(string.utf8)
          
          if let outputImage = filter.outputImage {
              let transform = CGAffineTransform(scaleX: 10, y: 10)
              let scaledImage = outputImage.transformed(by: transform)
              
              if let cgImage = context.createCGImage(scaledImage, from: scaledImage.extent) {
                  return UIImage(cgImage: cgImage)
              }
          }
          
          return UIImage(systemName: "xmark.circle") ?? UIImage()
      }
  }`.trim()
            }, null, 2)
          }]
        };
      } catch (error) {
        return {
          content: [{
            type: 'text',
            text: JSON.stringify({
              success: false,
              error: error instanceof Error ? error.message : 'Unknown error'
            }, null, 2)
          }],
          isError: true
        };
      }
    }

• src/tools/generateInvoice.ts:9-28 (schema)

  Input schema defining the parameters for generating the invoice: amountSats (required number >=1), optional description (string), optional expirySeconds (number, default 3600).

  inputSchema: {
    type: 'object',
    properties: {
      amountSats: {
        type: 'number',
        description: 'Amount in satoshis',
        minimum: 1
      },
      description: {
        type: 'string',
        description: 'Invoice description'
      },
      expirySeconds: {
        type: 'number',
        description: 'Invoice expiry time in seconds (default: 3600)',
        default: 3600
      }
    },
    required: ['amountSats']
  },

• src/index.ts:38-62 (registration)

  Registration of the tool in the main tools array used by the MCP server for handling listTools and callTool requests.

  const tools = [
    generateInvoiceTool,
    payInvoiceTool,
    getChannelStatusTool,
    getNodeInfoTool,
    backupStateTool,
    keychainTestTool,
    backgroundTestTool,
    pushNotificationTool,
    biometricAuthTool,
    createChannelTool,
    closeChannelTool,
    getBalanceTool,
    decodeInvoiceTool,
    listPaymentsTool,
    estimateFeeTool,
    generateMnemonicTool,
    deriveAddressTool,
    getSwiftCodeTool,
    getArchitectureTool,
    testScenarioTool,
    networkGraphTool,
    eventHandlingTool,
    chainSyncTool,
  ];

• src/index.ts:13-13 (registration)

  Import of the generateInvoiceTool for registration in the MCP server.

  import { generateInvoiceTool } from './tools/generateInvoice.js';