mcp-data-extractor

Instructions

Implementation Reference

• src/index.ts:63-79 (registration)

  Registers the 'extract_data' tool in the ListTools response, including name, detailed description, and input schema.
  name: 'extract_data', description: 'Extract data content (e.g. i18n translations) from source code to a JSON file. IMPORTANT: When encountering files with data such as i18n content embedded in code, use this tool directly instead of reading the file content first. This tool will programmatically extract all translations into a structured JSON file, preserving nested objects, arrays, template variables, and formatting. This helps keep translations as configuration and prevents filling up the AI context window with translation content. By default, the source file will be replaced with "MIGRATED TO <target absolute path>" and a warning message after successful extraction, making it easy to track where the data was moved to. This behaviour can be disabled by setting the DISABLE_SOURCE_REPLACEMENT environment variable to \'true\'. The warning message can be customized by setting the WARNING_MESSAGE environment variable.', inputSchema: { type: 'object', properties: { sourcePath: { type: 'string', description: 'Path to the source file containing data inside code', }, targetPath: { type: 'string', description: 'Path where the resulting JSON file should be written', }, }, required: ['sourcePath', 'targetPath'], }, },
• src/index.ts:65-78 (schema)

  Input schema for the 'extract_data' tool, defining required sourcePath and targetPath parameters.
  inputSchema: { type: 'object', properties: { sourcePath: { type: 'string', description: 'Path to the source file containing data inside code', }, targetPath: { type: 'string', description: 'Path where the resulting JSON file should be written', }, }, required: ['sourcePath', 'targetPath'], },
• src/index.ts:111-145 (handler)

  Executes the 'extract_data' tool: reads source file, extracts data content, writes to target JSON file, optionally replaces source with migration notice, and returns success message.
  if (request.params.name === 'extract_data') { const { targetPath } = request.params.arguments as { targetPath: string }; const dataContent = await this.extractDataContent(sourceCode); // Create target directory if it doesn't exist await fs.mkdir(path.dirname(targetPath), { recursive: true }); // Write extracted content to JSON file await fs.writeFile( targetPath, JSON.stringify(dataContent, null, 2), 'utf-8' ); // Replace source file content with migration message if not disabled if (!DISABLE_SOURCE_REPLACEMENT) { const absoluteTargetPath = path.resolve(targetPath); await fs.writeFile( sourcePath, `MIGRATED TO ${absoluteTargetPath}${WARNING_MESSAGE}`, 'utf-8' ); } return { content: [ { type: 'text', text: `Successfully extracted ${Object.keys(dataContent).length} data entries to ${path.resolve(targetPath)}${ !DISABLE_SOURCE_REPLACEMENT ? `. Source file replaced with "MIGRATED TO ${path.resolve(targetPath)}"` : '' }`, }, ], }; } else if (request.params.name === 'extract_svg') {
• src/index.ts:297-353 (handler)

  Core extraction logic: Parses source code AST with Babel, traverses to default export object, recursively extracts string values from nested objects/arrays using dot-notated keys.
  private async extractDataContent(sourceCode: string): Promise<Record<string, string | string[] | Array<Record<string, string | string[]>>>> { const ast = parser.parse(sourceCode, { sourceType: 'module', plugins: ['typescript', 'jsx'], }); const result: Record<string, any> = {}; const processValue = (value: t.Node, currentPath: string[]): void => { if (t.isStringLiteral(value) || t.isTemplateLiteral(value)) { const extractedValue = this.extractStringValue(value); if (extractedValue !== null && extractedValue.trim() !== '') { result[this.buildKey(currentPath)] = extractedValue; } } else if (t.isArrayExpression(value)) { value.elements.forEach((element, index) => { if (!element) return; if (t.isStringLiteral(element) || t.isTemplateLiteral(element)) { const extractedValue = this.extractStringValue(element); if (extractedValue !== null && extractedValue.trim() !== '') { result[`${this.buildKey(currentPath)}.${index}`] = extractedValue; } } else if (t.isObjectExpression(element)) { processObject(element, [...currentPath, index.toString()]); } }); } else if (t.isObjectExpression(value)) { processObject(value, currentPath); } }; const processObject = (obj: t.ObjectExpression, parentPath: string[] = []): void => { obj.properties.forEach(prop => { if (!t.isObjectProperty(prop)) return; const key = t.isIdentifier(prop.key) ? prop.key.name : t.isStringLiteral(prop.key) ? prop.key.value : null; if (!key) return; const currentPath = [...parentPath, key]; processValue(prop.value, currentPath); }); }; traverse(ast, { ExportDefaultDeclaration(path: NodePath<t.ExportDefaultDeclaration>) { const declaration = path.node.declaration; if (t.isObjectExpression(declaration)) { processObject(declaration); } } }); return result; }