Stacks Clarity MCP Server

Instructions

Implementation Reference

• src/tools/stacks_blockchain/security/post_conditions.ts:53-127 (handler)

  The main handler for the 'generate_fungible_post_condition' tool. This is the execute function that generates TypeScript code, Clarity requirements, and security notes for fungible token post-conditions based on input parameters.

  export const generateFungiblePostConditionTool: Tool<undefined, typeof FungiblePostConditionScheme> = {
    name: "generate_fungible_post_condition",
    description: "Generate a fungible token post-condition for SIP-010 tokens. Post-conditions are MANDATORY for all token transfers.",
    parameters: FungiblePostConditionScheme,
    execute: async (args, context) => {
      try {
        await recordTelemetry({ action: "generate_fungible_post_condition" }, context);
        
        return `# Fungible Token Post-Condition
  
  ## Configuration
  - **Principal**: ${args.principal}
  - **Condition**: ${args.conditionCode}
  - **Amount**: ${args.amount} base units
  - **Asset**: ${args.contractAddress}.${args.contractName}.${args.assetName}
  
  ## TypeScript Implementation
  
  \`\`\`typescript
  import {
    makeStandardFungiblePostCondition,
    FungibleConditionCode,
    createAssetInfo
  } from '@stacks/transactions';
  
  const postCondition = makeStandardFungiblePostCondition(
    '${args.principal}',
    FungibleConditionCode.${args.conditionCode.charAt(0).toUpperCase() + args.conditionCode.slice(1).replace('_', '')},
    ${args.amount},
    createAssetInfo(
      '${args.contractAddress}',
      '${args.contractName}',
      '${args.assetName}'
    )
  );
  
  // Use in transaction
  const postConditions = [postCondition];
  
  await openContractCall({
    // ... other parameters
    postConditions,
    postConditionMode: PostConditionMode.Deny, // REQUIRED for security
  });
  \`\`\`
  
  ## Clarity Contract Requirements
  
  For this post-condition to work, the contract must use native asset functions:
  
  \`\`\`clarity
  ;; REQUIRED: Native fungible token definition
  (define-fungible-token ${args.assetName})
  
  ;; REQUIRED: Use ft-transfer? for transfers
  (define-public (transfer (amount uint) (sender principal) (recipient principal) (memo (optional (buff 34))))
    (begin
      ;; ... validation logic ...
      (try! (ft-transfer? ${args.assetName} amount sender recipient))
      ;; ... rest of function ...
    )
  )
  \`\`\`
  
  ## Security Notes
  - ✅ This post-condition guarantees ${args.conditionCode === 'equal' ? 'exactly' : args.conditionCode} ${args.amount} tokens will be involved
  - ✅ Transaction will fail if condition is not met
  - ✅ Protects against unexpected token movements
  - ⚠️  Always use PostConditionMode.Deny for maximum security`;
        
      } catch (error) {
        return `❌ Failed to generate fungible post-condition: ${error}`;
      }
    },
  };

• src/tools/stacks_blockchain/security/post_conditions.ts:14-21 (schema)

  Zod schema defining the input parameters for the generate_fungible_post_condition tool: principal, conditionCode, amount, contractAddress, contractName, assetName.

  const FungiblePostConditionScheme = z.object({
    principal: z.string().describe("The Stacks address for the post-condition"),
    conditionCode: FungibleConditionCodeScheme.describe("The condition type (usually 'equal' for exact transfers)"),
    amount: z.number().describe("The token amount in base units"),
    contractAddress: z.string().describe("The token contract address"),
    contractName: z.string().describe("The token contract name"),
    assetName: z.string().describe("The token asset name (usually same as contract name)"),
  });

• src/tools/index.ts:60-60 (registration)

  Registration of the generateFungiblePostConditionTool in the MCP server via server.addTool call.

  server.addTool(generateFungiblePostConditionTool);

• src/tools/index.ts:19-24 (registration)

  Import of the generateFungiblePostConditionTool from its implementation file.

    generateFungiblePostConditionTool,
    generateNonFungiblePostConditionTool,
    generateSTXPostConditionTool,
    analyzeTransactionPostConditionsTool,
    generatePostConditionTemplateTool
  } from "./stacks_blockchain/security/post_conditions.js";