ModelRefs / File Read Tool — Tool Pattern
File Read Tool — Tool Pattern
Expose scoped file reads with path allowlists, size caps, and content-type sniffing so the model can inspect documents.
Overview
Tool: read_file(path, range?). The runtime enforces an allowlisted root, size caps, and content-type sniffing before returning text or a binary reference.
When to use it: You need the model to read user-supplied or workspace files safely.
Pattern details
| Pattern class | file-system |
|---|---|
| Difficulty | beginner |
| Invocation mode | synchronous |
| Also known as | fs read tool |
| Last reviewed | 2026-06-07 |
Known failure modes
- Path traversal — Model attempts ../ escapes. Mitigation: Canonicalize and validate against root.
- Huge file — Read blows the context window. Mitigation: Enforce size cap; return summary + handle.
When not to use it
- Letting the model read arbitrary filesystem paths.
Continue your research
Use these connected ModelRefs sections to compare alternatives, inspect implementation paths, and review the evidence and governance boundaries relevant to File Read Tool — Tool Pattern.
Frequently asked questions
When should I use the File Read Tool tool pattern?
You need the model to read user-supplied or workspace files safely.
What are common failure modes of File Read Tool?
Path traversal • Huge file
Is File Read Tool production-ready?
Yes when paired with the safety controls and observability hooks documented on the pattern page.