W3Ship MCP Server

Instructions

Implementation Reference

• src/index.ts:838-916 (handler)

  The handler implementation for the check_token_approval tool in src/index.ts.

  case 'check_token_approval': {
      if (!UNISWAP_API_KEY) {
          return {
              content: [{ type: 'text', text: 'Error: UNISWAP_API_KEY environment variable is not set. Get your API key at https://developers.uniswap.org' }],
              isError: true,
          };
      }
  
      const { token: tokenArg, amount: approveAmount, walletAddress: approveWallet, chainId: approveChain } = args as any;
      const appChainId = approveChain || 8453;
      const appWallet = approveWallet || CONFIGURED_KEY;
  
      if (!appWallet) {
          return {
              content: [{ type: 'text', text: 'Error: Wallet address required. Set W3SHIP_PUBLIC_KEY or provide walletAddress.' }],
              isError: true,
          };
      }
  
      const resolveTokenAddr = (t: string) => {
          const upper = t.toUpperCase();
          return TOKENS[upper]?.address || t;
      };
      const resolveTokenDec = (t: string) => {
          const upper = t.toUpperCase();
          return TOKENS[upper]?.decimals || 18;
      };
  
      const tokenAddr = resolveTokenAddr(tokenArg);
      const tokenDec = resolveTokenDec(tokenArg);
      const approveAmountRaw = BigInt(Math.floor(parseFloat(approveAmount) * (10 ** tokenDec))).toString();
  
      try {
          const approvalRes = await fetch(`${UNISWAP_API}/check_approval`, {
              method: 'POST',
              headers: {
                  'Content-Type': 'application/json',
                  'x-api-key': UNISWAP_API_KEY,
              },
              body: JSON.stringify({
                  token: tokenAddr,
                  amount: approveAmountRaw,
                  walletAddress: appWallet,
                  chainId: appChainId,
              }),
          });
  
          const approvalData = await approvalRes.json() as any;
  
          if (!approvalRes.ok) {
              return {
                  content: [{ type: 'text', text: `Uniswap API error: ${approvalData.errorCode || JSON.stringify(approvalData)}` }],
                  isError: true,
              };
          }
  
          return {
              content: [{
                  type: 'text',
                  text: JSON.stringify({
                      token: tokenArg.toUpperCase(),
                      amount: approveAmount,
                      chainId: appChainId,
                      approved: approvalData.approved || false,
                      approvalNeeded: !approvalData.approved,
                      approvalTransaction: approvalData.approvalTransaction || null,
                      message: approvalData.approved
                          ? `${tokenArg.toUpperCase()} is already approved for swapping`
                          : `${tokenArg.toUpperCase()} needs approval before swapping. Transaction data provided.`,
                  }, null, 2)
              }]
          };
      } catch (e: any) {
          return {
              content: [{ type: 'text', text: `Error checking approval: ${e.message}` }],
              isError: true,
          };
      }
  }

• src/index.ts:236-248 (registration)

  Tool registration for check_token_approval in src/index.ts.

      name: 'check_token_approval',
      description: 'Check if a token is approved for swapping on Uniswap. Returns whether approval is needed and the approval transaction if so. Requires UNISWAP_API_KEY env var.',
      inputSchema: {
          type: 'object',
          properties: {
              token: { type: 'string', description: 'Token symbol (USDC, USDT, DAI, WETH) or contract address' },
              amount: { type: 'string', description: 'Amount to approve (in human-readable units)' },
              walletAddress: { type: 'string', description: 'Wallet address. Uses W3SHIP_PUBLIC_KEY if not provided.' },
              chainId: { type: 'number', description: 'Chain ID (default: 8453 for Base)' },
          },
          required: ['token', 'amount'],
      },
  },