diff --git a/action.yml b/action.yml
index 9b7cc05..ec5c38c 100644
--- a/action.yml
+++ b/action.yml
@@ -124,7 +124,8 @@ runs:
         mcp_config: ${{ steps.prepare.outputs.mcp_config }}
         use_bedrock: ${{ inputs.use_bedrock }}
         use_vertex: ${{ inputs.use_vertex }}
-        anthropic_api_key: ${{ inputs.anthropic_api_key }}
+        # Don't pass anthropic_api_key when using OAuth
+        anthropic_api_key: ${{ inputs.anthropic_api_key != 'use-oauth' && inputs.anthropic_api_key || '' }}
       env:
         # Core configuration
         PROMPT_FILE: /tmp/claude-prompts/claude-prompt.txt