# Knowledge attachment

**Source:** https://promtable.com/glossary/knowledge-attachment

> A knowledge attachment is the file uploaded to a custom persona (ChatGPT GPT, Claude Project, Gemini Gem) that the LLM retrieves over at inference — turning custom personas into mini RAG apps without writing retrieval code.

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A knowledge attachment is the file uploaded to a custom persona (ChatGPT GPT, Claude Project, Gemini Gem) that the LLM retrieves over at inference — turning custom personas into mini RAG apps without writing retrieval code.

Knowledge attachments make custom-persona platforms RAG-capable out of the box: upload PDFs, docs, CSVs, the platform indexes them, retrieval happens automatically per turn. Limits vary by platform: ChatGPT GPTs accept up to 20 files (~2MB each), Claude Projects accepts ~100MB, Gemini Gems take files via the Gemini app. Production gotchas: retrieval quality varies (semantic vs keyword), attachment-content-extraction can mangle complex PDFs (tables, scanned docs), no fine-grained access control (per-attachment auth), updates require re-uploading. For high-quality RAG production teams still build their own pipeline. For internal team knowledge bases knowledge attachments are 'good enough' to ship in a day.

## When to use

- Quick internal-knowledge bots.
- Small-scale RAG personas without backend code.

## Common mistakes

- Trusting attachment retrieval quality on complex PDFs — tables and scanned docs degrade.
- Treating uploaded files as access-controlled — anyone with the persona link can extract them.

## Related terms

- [rag](https://promtable.com/glossary/rag)
- [vector-database](https://promtable.com/glossary/vector-database)
- [custom-instruction](https://promtable.com/glossary/custom-instruction)

*Last updated: 2026-06-01*
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Original page: https://promtable.com/glossary/knowledge-attachment
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