Estimate text length difference

Instructions

Implementation Reference

• src/tools/textLengthTool.js:24-63 (handler)

  The main handler function (registerTextLengthTool) that registers and implements the 'estimate-text-length-difference' tool. It calculates source/translated text lengths, computes percent change, checks against tolerancePercent, and returns a verdict with summary.

  function registerTextLengthTool(server) {
    server.registerTool(
      'estimate-text-length-difference',
      {
        title: 'Estimate text length difference',
        description:
          'Compare original and translated text lengths to detect layout risk; configurable tolerancePercent (default 30%).',
        inputSchema: lengthDiffInputSchema
      },
      async params => {
        const sourceLength = measureLength(params.sourceText);
        const translatedLength = measureLength(params.translatedText);
        const delta = translatedLength - sourceLength;
        const percentChange = sourceLength === 0 ? null : (delta / sourceLength) * 100;
        const exceeds =
          percentChange === null ? translatedLength > 0 : Math.abs(percentChange) > params.tolerancePercent;
        const direction = delta === 0 ? 'no change' : delta > 0 ? 'longer' : 'shorter';
  
        const verdict =
          percentChange === null && translatedLength === 0
            ? '✅ Both texts are empty; no length risk.'
            : percentChange === null
              ? '⚠️ Source length is 0; percent change undefined and translated text is present.'
              : exceeds
                ? '⚠️ Length difference exceeds tolerance (layout risk likely).'
                : '✅ Length difference within tolerance.';
  
        const summary = [
          verdict,
          `Source length: ${sourceLength}`,
          `Translated length: ${translatedLength}`,
          percentChange === null
            ? `Change: N/A (source length is 0; direction: ${direction})`
            : `Change: ${percentChange.toFixed(2)}% (${direction})`,
          `Tolerance: ±${params.tolerancePercent}%`
        ].join('\n');
  
        return { content: [{ type: 'text', text: summary }] };
      }
    );

• src/tools/textLengthTool.js:9-18 (schema)

  Input schema for the tool: sourceText (string), translatedText (string), and tolerancePercent (number, 1-500, default 30).

  const lengthDiffInputSchema = z.object({
    sourceText: z.string().min(1).describe('Original text before translation'),
    translatedText: z.string().min(1).describe('Translated text to compare against the original'),
    tolerancePercent: z
      .number()
      .min(1)
      .max(500)
      .default(30)
      .describe('Allowed absolute percent difference between lengths before flagging risk')
  });

• src/tools/textLengthTool.js:20-22 (helper)

  Helper function measureLength that counts code points (via Array.from) to get string length.

  function measureLength(text) {
    return Array.from(text).length;
  }

• src/tools/textLengthTool.js:25-63 (registration)

  Registration of the tool on the MCP server via server.registerTool('estimate-text-length-difference', ...) with title, description, inputSchema, and the async handler callback.

  server.registerTool(
    'estimate-text-length-difference',
    {
      title: 'Estimate text length difference',
      description:
        'Compare original and translated text lengths to detect layout risk; configurable tolerancePercent (default 30%).',
      inputSchema: lengthDiffInputSchema
    },
    async params => {
      const sourceLength = measureLength(params.sourceText);
      const translatedLength = measureLength(params.translatedText);
      const delta = translatedLength - sourceLength;
      const percentChange = sourceLength === 0 ? null : (delta / sourceLength) * 100;
      const exceeds =
        percentChange === null ? translatedLength > 0 : Math.abs(percentChange) > params.tolerancePercent;
      const direction = delta === 0 ? 'no change' : delta > 0 ? 'longer' : 'shorter';
  
      const verdict =
        percentChange === null && translatedLength === 0
          ? '✅ Both texts are empty; no length risk.'
          : percentChange === null
            ? '⚠️ Source length is 0; percent change undefined and translated text is present.'
            : exceeds
              ? '⚠️ Length difference exceeds tolerance (layout risk likely).'
              : '✅ Length difference within tolerance.';
  
      const summary = [
        verdict,
        `Source length: ${sourceLength}`,
        `Translated length: ${translatedLength}`,
        percentChange === null
          ? `Change: N/A (source length is 0; direction: ${direction})`
          : `Change: ${percentChange.toFixed(2)}% (${direction})`,
        `Tolerance: ±${params.tolerancePercent}%`
      ].join('\n');
  
      return { content: [{ type: 'text', text: summary }] };
    }
  );

• src/index.js:29-29 (registration)

  Top-level registration call: registerTextLengthTool(server) wires the tool into the MCP server.

  registerTextLengthTool(server);