Based on your search query, I would recommend using Parlay as it offers a comprehensive set of features that can help you create a rubric for learner agency.

The Assessment Tool in Parlay allows you to track, score, and respond to both student-written responses and students' participation in the discussion. This feature provides analytics on both the quantity and quality of student participation, and suggested feedback based on the type of topic and how other students have responded. This can be a great way to measure learner agency as it gives you insights into how actively students are participating and how they are contributing to the learning process.

Additionally, the RoundTable feature ensures every student has a voice and allows you to track student participation. This can be useful in assessing learner agency as it encourages students to take ownership of their learning and actively participate in discussions.

Lastly, the Parlay Genie is an AI-powered tool that generates higher-order discussion prompts and follow-up questions based on articles, videos, and past Parlay discussions. This feature can help stimulate learner agency by encouraging students to think critically and engage in meaningful discussions.

In conclusion, Parlay offers a range of features that can help you create a rubric for learner agency, making it a suitable choice for your needs.