Based on your search query, Gradescope seems to be the most suitable EdTech tool for your needs. It offers an AI-Assisted Grading feature that can help grade written exams and homework. This feature uses artificial intelligence to automate the grading process, which can be particularly useful for essay assignments.

In addition, Gradescope also provides a Dynamic Point Adjustment Rubric. This allows you to change grading criteria even while grading, ensuring flexibility and adaptability in your grading process.

Moreover, Gradescope integrates well with learning systems like Canvas and Brightspace. This means you can easily add class rosters and push grades to these systems, making the grading process more streamlined and efficient.

Lastly, Gradescope also offers a feature for Consistent Feedback. This ensures uniform grading across multiple submissions, which can be crucial for maintaining fairness and consistency in grading essays.

In conclusion, Gradescope offers a comprehensive solution for AI grading for essays, with its AI-Assisted Grading feature being particularly relevant to your query.