openclaw - 💡(How to fix) Fix read tool output truncated for medium-sized files (2026.5.18 regression)

Summary

The read tool truncates file content at a lower threshold than expected after the 2026.5.18 update. When reading a 365-line / 8737-byte SKILL.md file, the output appeared incomplete in the agent's context — content that was fully returned by the tool was either truncated by the context window or by a new tool output cap introduced in the update.

Impact

• Agents cannot reliably read medium-sized files (even <10KB) and get the full content
• Task-relevant information may be silently lost
• Debugging and configuration-reading workflows are degraded

Additional context

This may be related to the 2026.5.18 change: "Agents/tools: shorten built-in tool descriptions and schema hints" — if the read tool's schema hint was shortened in a way that affects how the agent or runtime handles output, that could explain the regression. Alternatively, the update may have introduced a hard output cap on tool results.

Environment

• OpenClaw version: 2026.5.18 (upgraded from 2026.5.17)
• File read: 365 lines, 8737 bytes (well within typical limits)
• No explicit error message — content was simply not delivered in full