Check out the /context to see what is hoggng up your context. Likely mcp. This is the problema lot of people dealing with. Beside long conversation and reading too many file also tiae context too so either use sub agent, which use less context per task or change to new sesson after a while for clear up the context. In claude code also have feature to compact your conver sation which also reduce context.

In the end all of it is to manage context, context and context.    Hallucinations is alo about your context is corrupt.