how to instruct agent to use both LSP & fff?

[charger89]

similar to #788

fff readme instructs us to provide agent with following instruction:

For any file search or grep in the current git-indexed directory, use fff tools.

This would likely collide with other MCP tools, such as LSPs. What would be the optimal way of instructing agent to first rely on LSP, and only use fff if it tries to fall back to grep/find et al?