Fix double instantiation of planner tool and improve README.md grammar and consistency

[Anionex]

Update README.md:

• Fixed typos and grammar issues.
• Improved clarity and consistency of the documentation.

Update tool_agents.py:

• Fix double instantiation of planner tool by adding a conditional check.

appreciate your work:) hope to have the opportunity to participate in related research topics as well.

[hsaest]

Thanks for your PR which helps a lot. Feel free to contact us if you are interested in some of our works.