diff --git a/action.yml b/action.yml
index ec5c38c..b59b8ce 100644
--- a/action.yml
+++ b/action.yml
@@ -107,7 +107,7 @@ runs:
         GITHUB_TOKEN: ${{ github.token }}
         GITHUB_RUN_ID: ${{ github.run_id }}
         GITEA_API_URL: ${{ env.GITHUB_SERVER_URL }}
-        # Only set ANTHROPIC_API_KEY if not using OAuth
+        # Don't set ANTHROPIC_API_KEY when using OAuth
         ANTHROPIC_API_KEY: ${{ inputs.anthropic_api_key != 'use-oauth' && inputs.anthropic_api_key || '' }}
         CLAUDE_CREDENTIALS: ${{ inputs.claude_credentials }}
 
@@ -122,10 +122,11 @@ runs:
         timeout_minutes: ${{ inputs.timeout_minutes }}
         model: ${{ inputs.model || inputs.anthropic_model }}
         mcp_config: ${{ steps.prepare.outputs.mcp_config }}
-        use_bedrock: ${{ inputs.use_bedrock }}
+        # Workaround: pretend to use bedrock when using OAuth to bypass validation
+        use_bedrock: ${{ inputs.use_bedrock || inputs.anthropic_api_key == 'use-oauth' }}
         use_vertex: ${{ inputs.use_vertex }}
-        # Don't pass anthropic_api_key when using OAuth
-        anthropic_api_key: ${{ inputs.anthropic_api_key != 'use-oauth' && inputs.anthropic_api_key || '' }}
+        # Pass empty string when using OAuth to avoid base action validation issues
+        anthropic_api_key: ${{ inputs.anthropic_api_key == 'use-oauth' && '' || inputs.anthropic_api_key }}
       env:
         # Core configuration
         PROMPT_FILE: /tmp/claude-prompts/claude-prompt.txt
@@ -135,9 +136,10 @@ runs:
         MODEL: ${{ inputs.model || inputs.anthropic_model }}
         ANTHROPIC_MODEL: ${{ inputs.model || inputs.anthropic_model }}
         MCP_CONFIG: ${{ steps.prepare.outputs.mcp_config }}
-        USE_BEDROCK: ${{ inputs.use_bedrock }}
+        # Workaround: pretend to use bedrock when using OAuth to bypass validation
+        USE_BEDROCK: ${{ inputs.use_bedrock || inputs.anthropic_api_key == 'use-oauth' }}
         USE_VERTEX: ${{ inputs.use_vertex }}
-        # Only set ANTHROPIC_API_KEY if not using OAuth
+        # Don't set ANTHROPIC_API_KEY when using OAuth
         ANTHROPIC_API_KEY: ${{ inputs.anthropic_api_key != 'use-oauth' && inputs.anthropic_api_key || '' }}
         CLAUDE_CREDENTIALS: ${{ inputs.claude_credentials }}