Conversation so far:
Who played Yoda
Frank Oz provided Yoda's voice in each film and used his skills as a puppeteer in the original trilogy and Star Wars: Episode I – The Phantom Menace.
Why was Yoda important in Star Wars Episode III: Revenge of the Sith?
In Revenge of the Sith, Yoda leads the Jedi Council in pursuing the mysterious Sith Lord Darth Sidious.
Was Yoda succesful in pursuing the mysterious Sith Lord Darth Sidious?
He goes into exile on Dagobah so that he may hide from the Empire and wait for another opportunity to destroy the Sith.
What else did Yoda do in Star Wars Episode III: Revenge of the Sith besides pursuing the mysterious Sith Lord Darh Sidious?
Yoda and The Jedi Council order Anakin to spy on Palpatine, whom Anakin considers a friend and mentor.

Question: why did they spy on Palpatine
Self-contained rewrite: why the Jedi Council led by Yoda spy on Palpatine