Your system prompt is too big
Resolved 💬 2 comments Opened Apr 23, 2026 by alex-jitbit Closed Apr 23, 2026
💡 Likely answer: A maintainer (github-actions[bot], contributor)
responded on this thread — see the highlighted reply below.
What version of the IDE extension are you using?
26.417.40842
What subscription do you have?
Plus
Which IDE are you using?
VSCode/.Cursor (same)
What platform is your computer?
_No response_
What issue are you seeing?
I am trying Codex (after years of using Cursor and months of Claude Code) and the system prompt looks bloated.
Asking a simple question "what is 2+2" consumes ~13k (13 thousand!) tokens. I don't have any skills, custom prompts, MCPs, my project's agents.md is 30 lines (500 tokens).
I interrogated Codex to tell me how big the system instructions are and it says:
A reasonable estimate for this session is:
* System instructions: 2k-4k
* Web/browsing policy and source-handling rules: 3k-5k
* Developer instructions for coding behavior/style/workflow: 3k-5k
* Tool schemas and tool descriptions: 2k-4k
* AGENTS.md and environment context: 0.5k-1k
* Your actual message: under 100Pardon my French, this is nuts.
What steps can reproduce the bug?
Ask "What is 2+2" in VScode extension, see this
<img width="199" height="153" alt="Image" src="https://github.com/user-attachments/assets/705af6f7-7556-42e7-8136-9f5b2efa6c21" />
What is the expected behavior?
_No response_
Additional information
_No response_
2 Comments
Potential duplicates detected. Please review them and close your issue if it is a duplicate.
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Yes, this is the size of the system prompt in a modern coding harness. We are trying hard to keep the size to a reasonable minimum even as we add new functionality.