TypeScript Definitions MCP Server

Instructions

Implementation Reference

• src/type-validator.ts:11-79 (handler)

  Core implementation of the validate_type_usage tool logic using TypeScript Compiler API to create a temporary program, check syntactic/semantic diagnostics, and validate against an optional expected type.
  validateTypeUsage(code: string, expectedType?: string): ValidationResult { const errors: ValidationError[] = []; const warnings: ValidationWarning[] = []; try { // Create a temporary source file for validation const sourceFile = ts.createSourceFile( "temp.ts", code, ts.ScriptTarget.Latest, true ); // Create a program with just this file const defaultCompilerHost = ts.createCompilerHost(this.compilerOptions); const compilerHost = { ...defaultCompilerHost, getSourceFile: (fileName: string, languageVersion: ts.ScriptTarget) => { if (fileName === "temp.ts") { return sourceFile; } return defaultCompilerHost.getSourceFile(fileName, languageVersion); } }; const program = ts.createProgram(["temp.ts"], this.compilerOptions, compilerHost); // Get semantic diagnostics const semanticDiagnostics = program.getSemanticDiagnostics(sourceFile); const syntacticDiagnostics = program.getSyntacticDiagnostics(sourceFile); // Convert diagnostics to our format for (const diagnostic of [...syntacticDiagnostics, ...semanticDiagnostics]) { const message = ts.flattenDiagnosticMessageText(diagnostic.messageText, "\n"); const position = diagnostic.start ? sourceFile.getLineAndCharacterOfPosition(diagnostic.start) : undefined; const errorInfo = { message, line: position ? position.line + 1 : undefined, column: position ? position.character + 1 : undefined, code: diagnostic.code?.toString() }; if (diagnostic.category === ts.DiagnosticCategory.Error) { errors.push(errorInfo); } else if (diagnostic.category === ts.DiagnosticCategory.Warning) { warnings.push(errorInfo); } } // If expected type is provided, validate against it if (expectedType && errors.length === 0) { const typeChecker = program.getTypeChecker(); this.validateExpectedType(sourceFile, typeChecker, expectedType, errors, warnings); } } catch (error) { errors.push({ message: `Validation failed: ${error instanceof Error ? error.message : String(error)}`, code: "VALIDATION_ERROR" }); } return { valid: errors.length === 0, errors, warnings }; }
• src/mcp-server.ts:292-303 (handler)

  MCP server handler method for validate_type_usage tool that delegates to TypeValidator and formats the result as MCP response.
  private async handleValidateTypeUsage(code: string, expectedType?: string) { const result = this.typeValidator.validateTypeUsage(code, expectedType); return { content: [ { type: "text", text: JSON.stringify(result, null, 2) } ] }; }
• src/mcp-server.ts:95-111 (registration)

  Tool registration in the ListTools response, defining name, description, and input schema.
  name: "validate_type_usage", description: "Validate TypeScript code for type correctness", inputSchema: { type: "object", properties: { code: { type: "string", description: "The TypeScript code to validate" }, expectedType: { type: "string", description: "Optional expected type to validate against" } }, required: ["code"] } },
• src/mcp-server.ts:15-27 (schema)

  TypeScript interface defining the expected arguments for the validate_type_usage tool, used for internal type safety.
  interface ToolArguments { lookup_type: { typeName: string; packageName?: string }; validate_type_usage: { code: string; expectedType?: string }; find_interfaces: { pattern: string }; get_package_types: { packageName: string }; validate_interface_implementation: { implementation: string; interfaceName: string; interfaceDefinition: string; }; check_type_compatibility: { sourceType: string; targetType: string }; reinitialize_indexer: { workingDir?: string }; }
• src/mcp-server.ts:217-220 (registration)

  Tool dispatch registration in the CallToolRequest handler switch statement.
  case "validate_type_usage": { const validateArgs = this.validateArgs<ToolArguments["validate_type_usage"]>(args); return await this.handleValidateTypeUsage(validateArgs.code, validateArgs.expectedType); }