Which model for long-context work

The decision

Large context helps only if the model can use the right part of it. Choose based on document type, needed answer, source-grounding requirements, and whether the workflow must keep state across many turns. If “context window” or token budget is new to you, start with tokens and context windows.

Claude is often a strong first choice for long written documents and careful synthesis. Gemini is useful when long context includes mixed media or Google AI Studio/API workflows. ChatGPT is a strong fit when large-document work needs tools, structured extraction, or a broader OpenAI workflow.

Prompt shape

For long documents, the prompt should say what to ignore as clearly as what to inspect.

Read the attached implementation plan for approval risk.

Ignore background history unless it changes the approval decision. Focus on migration
steps, rollback plan, data risk, and missing owners. Cite the section name for each
blocking concern.

Context management

Large-window prompts still need source names, section boundaries, and summaries of prior decisions. OpenAI’s compaction docs and Claude’s context-window docs both treat context management as part of longer workflows, not an afterthought.

For the recipe version, see long-document summarization.

What to avoid

• Choosing the largest context window without checking answer quality.
• Pasting a document set with no source names.
• Asking for a generic summary when the reader needs a decision.
• Keeping old plans beside current requirements.