diff --git a/docs/usage.md b/docs/usage.md
index b3abfd6..6f995d1 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -132,7 +132,7 @@ def multiply(x: int, y: int) -> int:
     return x * y
 ' 'what is 34234 * 213345'
 ```
-Add `--td/--tools-debug` to see full details of the tools that are being executed:
+Add `--td/--tools-debug` to see full details of the tools that are being executed. You can also set the `LLM_TOOLS_DEBUG` environment variable to `1` to enable this for all prompts.
 ```bash
 llm --functions '
 def multiply(x: int, y: int) -> int:
diff --git a/llm/cli.py b/llm/cli.py
index 089c4c3..6ed5e16 100644
--- a/llm/cli.py
+++ b/llm/cli.py
@@ -354,6 +354,7 @@ def cli():
     "--tools-debug",
     is_flag=True,
     help="Show full details of tool executions",
+    envvar="LLM_TOOLS_DEBUG",
 )
 @click.option(
     "tools_approve",