diff --git a/model_tools.py b/model_tools.py
index a4ed0c20c5..dda40405b7 100644
--- a/model_tools.py
+++ b/model_tools.py
@@ -704,7 +704,11 @@ _TOOL_ERROR_ROLE_TAG_RE = re.compile(
 _TOOL_ERROR_FENCE_OPEN_RE = re.compile(r'^\s*```(?:json|xml|html|markdown)?\s*', re.MULTILINE)
 _TOOL_ERROR_FENCE_CLOSE_RE = re.compile(r'\s*```\s*$', re.MULTILINE)
 _TOOL_ERROR_CDATA_RE = re.compile(r'<!\[CDATA\[.*?\]\]>', re.DOTALL)
-_TOOL_ERROR_MAX_LEN = 2000
+# Single home for the tool-error context cap: tools/registry.py. Both this
+# sanitizer (exception paths) and the dispatch-boundary bounding
+# (tool_error / _bound_json_error_result) trim to the same budget so text
+# never passes two different caps with two different markers.
+from tools.registry import _MAX_TOOL_ERROR_CHARS as _TOOL_ERROR_MAX_LEN
 
 
 def _sanitize_tool_error(error_msg: str) -> str: