Based on your search query, I recommend Grammarly as a suitable EdTech tool. It's a digital writing assistant that can help you create business letter worksheets.

Here's how Grammarly can address your needs:

1. Grammar and Spell Checking: Grammarly can ensure your worksheets are free from grammar, punctuation, and spelling mistakes. This feature will help you maintain the quality of your teaching materials.

2. Stylistic and Best-Practice Writing Suggestions: This feature can help you improve the writing style of your worksheets, making them more engaging and effective for your students.

3. Real-Time Comments and Suggestions: As you create your worksheets, Grammarly provides real-time suggestions and explanations, aiding in the writing process.

4. Setting Goals: When you upload a document, Grammarly asks you to set your goals. This feature can help you tailor your worksheets based on your audience and domain.

Remember, Grammarly offers a free version that checks for errors. However, the premium version, which includes additional features, is available for $12 per month when billed annually. A business plan is also available for $15 per member per month, billed annually.

In conclusion, Grammarly can be a valuable tool for creating high-quality, error-free business letter worksheets.