I wrote a bit about this the other day: https://simonwillison.net/2025/Jun/27/context-engineering/ Drew Breunig has been doing some fantastic writing on this subject - coincidentally at the same time as the "context engineering" buzzword appeared but actually unrelated to that meme. How Long Contexts Fail - https://www.dbreunig.com/2025/06/22/how-contexts-fail-and-ho... - talks about the various ways in which longer…
From the first link:Read large enough context to ensure you get what you need. How does this actually work, and how can one better define this to further improve the prompt? This statement feels like the 'draw the rest of the fucking owl' referred to elsewhere in the thread
The "Read large enough context to ensure you get what you need" quote is from a different post entirely, this one: https://simonwillison.net/2025/Jun/30/vscode-copilot-chat/
That's part of the system prompts used by the GitHub Copilot Chat extension for VS Code - from this line: https://github.com/microsoft/vscode-copilot-chat/blob/40d039...
The full line is:
When using the {ToolName.ReadFile} tool, prefer reading a
large section over calling the {ToolName.ReadFile} tool many
times in sequence. You can also think of all the pieces you
may be interested in and read them in parallel. Read large
enough context to ensure you get what you need.
It makes more sense if you look at the definition of the ReadFile tool:
https://github.com/microsoft/vscode-copilot-chat/blob/40d039...
description: 'Read the contents of a file. Line numbers are
1-indexed. This tool will truncate its output at 2000 lines
and may be called repeatedly with offset and limit parameters
to read larger files in chunks.'