While using Google NotebookLM for my Master’s thesis research, I ran into an annoying problem: I had created a long and detailed prompt for analysing research papers, but NotebookLM would not submit it.
When the prompt became too long, clicking the send arrow appeared to do nothing. There was no useful error message. Shortening the prompt made it work again.
The Problem
For my literature review, I wanted NotebookLM to analyse each research paper using detailed instructions covering areas such as:
- dataset and date range
- target and input features
- preprocessing and scaling
- look-back window
- forecasting horizons
- LSTM, GRU and Transformer architectures
- training, validation and testing
- hyperparameter tuning
- evaluation metrics
- numerical results
- data leakage and look-ahead bias
- limitations and future work
- critical analysis
- relevance to my thesis
I also wanted the output in several predefined formats.
Naturally, the prompt became quite long.
Instead of continually shortening the instructions and potentially losing important requirements, I found a useful workaround from a discussion on Reddit.
The Trick: Store the Prompt as a Source
Instead of putting the entire prompt into NotebookLM’s chat box, create a document containing the full instructions.
I called mine: NotebookLM Task
Then upload that document to the NotebookLM notebook as a source.
The long instructions can remain inside that document while the actual chat prompt stays very short.
Using It With One Research Paper at a Time
For my literature review, I select only two sources:
- NotebookLM Task: contains the instructions
- The research paper currently being analysed: contains the evidence
All other research papers are deselected.
I then use this short prompt:
Follow the complete instructions in "NotebookLM Task".
Analyse the only selected research paper and complete Parts A, B, and C exactly as instructed.
Treat "NotebookLM Task" as instructions only, not as research evidence. The selected research paper is the only evidence source.
Use only the selected research paper for factual claims, results, methodology, limitations, and critical analysis.
For important methodological facts, numerical results, dataset details, and limitations, provide NotebookLM citations so I can verify them in the original paper.
If the paper does not report something requested in the task, write "Not reported." Do not infer, guess, or fill in missing information.This means I do not need to paste the large prompt again for every research paper.
For the next paper, I simply deselect the previous paper, select the next one, keep NotebookLM Task selected, and run the same short instruction again.
Why I Prefer This Approach
This has another advantage beyond working around long prompts.
Keeping only the instruction document and one research paper selected reduces the possibility of NotebookLM mixing information from several papers.
For systematic literature review work, this gives me a simple workflow:
- Long reusable instructions → NotebookLM Task
- Research evidence → One selected paper
- Chat query → Short instruction telling NotebookLM to execute the task
It also makes the analysis process more consistent because every paper is evaluated against the same master instructions.
Important Note
I would not treat any particular character or word count mentioned online as an official NotebookLM limit unless Google documents it.
The Reddit discussion that led me to this workaround contains different user experiences with prompt length. Therefore, the useful takeaway for me is not a specific numerical limit but the instruction-document workaround itself.
Source / Credit
I found this trick in a discussion on the r/notebooklm subreddit: Limit on query length? on r/notebooklm.
The suggestion was to place a long prompt into a source document such as “NotebookLM Task” and then use a much shorter chat query instructing NotebookLM to follow that document.
This note records how I adapted that idea for my own research workflow.
