fix(ai-proxy): preserve empty Claude tool inputs (#3799)

Signed-off-by: Betula-L <6059935+Betula-L@users.noreply.github.com>
Co-authored-by: Betula-L <6059935+Betula-L@users.noreply.github.com>

plugins/wasm-go/extensions/ai-proxy/provider/bedrock.go

@@ -1506,7 +1506,7 @@ func claudeContentBlocksToBedrockContents(blocks []claudeChatMessageContent) []b
 			}
 		case "tool_use":
 			result = append(result, bedrockMessageContent{ToolUse: &toolUseBlock{
-				Input:     block.Input,
+				Input:     claudeToolUseInput(block.Input),
 				Name:      block.Name,
 				ToolUseId: block.Id,
 			}})
@@ -1525,6 +1525,13 @@ func claudeContentBlocksToBedrockContents(blocks []claudeChatMessageContent) []b
 	return result
 }
 
+func claudeToolUseInput(input *map[string]interface{}) map[string]interface{} {
+	if input == nil {
+		return map[string]interface{}{}
+	}
+	return *input
+}
+
 func bedrockThinkingFromClaudeConfig(thinking *claudeThinkingConfig) map[string]interface{} {
 	if thinking == nil || thinking.Type == "" || thinking.Type == "disabled" {
 		return nil

plugins/wasm-go/extensions/ai-proxy/provider/bedrock_thinking_test.go

@@ -251,6 +251,35 @@ func TestBedrockRequestPreservesClaudeNativeThinkingAndToolResult(t *testing.T)
 	assert.Equal(t, "failed", *request.Messages[1].Content[0].ToolResult.Content[0].Text)
 }
 
+func TestBedrockRequestPreservesClaudeNoArgToolUseInput(t *testing.T) {
+	provider := &bedrockProvider{}
+	openaiBody, err := (&ClaudeToOpenAIConverter{}).ConvertClaudeRequestToOpenAI([]byte(`{
+		"model":"claude",
+		"messages":[{
+			"role":"assistant",
+			"content":[
+				{"type":"thinking","thinking":"reasoning","signature":"sig"},
+				{"type":"tool_use","id":"toolu_1","name":"list_items","input":{}}
+			]
+		}]
+	}`))
+	require.NoError(t, err)
+
+	var openaiRequest chatCompletionRequest
+	require.NoError(t, json.Unmarshal(openaiBody, &openaiRequest))
+
+	body, err := provider.buildBedrockTextGenerationRequest(&openaiRequest, nil)
+	require.NoError(t, err)
+
+	require.Contains(t, string(body), `"input":{}`)
+	var request bedrockTextGenRequest
+	require.NoError(t, json.Unmarshal(body, &request))
+	require.Len(t, request.Messages, 1)
+	require.Len(t, request.Messages[0].Content, 2)
+	require.NotNil(t, request.Messages[0].Content[1].ToolUse)
+	assert.Empty(t, request.Messages[0].Content[1].ToolUse.Input)
+}
+
 func TestBedrockRequestToolResultWithTrailingTextDoesNotDuplicateToolResult(t *testing.T) {
 	provider := &bedrockProvider{}
 	openaiBody, err := (&ClaudeToOpenAIConverter{}).ConvertClaudeRequestToOpenAI([]byte(`{

plugins/wasm-go/extensions/ai-proxy/provider/claude.go

@@ -70,9 +70,9 @@ type claudeChatMessageContent struct {
 	Source       *claudeChatMessageContentSource `json:"source,omitempty"`
 	CacheControl map[string]interface{}          `json:"cache_control,omitempty"`
 	// Tool use fields
-	Id    string                 `json:"id,omitempty"`    // For tool_use
-	Name  string                 `json:"name,omitempty"`  // For tool_use
-	Input map[string]interface{} `json:"input,omitempty"` // For tool_use
+	Id    string                  `json:"id,omitempty"`    // For tool_use
+	Name  string                  `json:"name,omitempty"`  // For tool_use
+	Input *map[string]interface{} `json:"input,omitempty"` // For tool_use
 	// Tool result fields
 	ToolUseId string                      `json:"tool_use_id,omitempty"` // For tool_result
 	Content   *claudeChatMessageContentWr `json:"content,omitempty"`     // For tool_result - can be string or array
@@ -622,7 +622,7 @@ func (c *claudeProvider) buildClaudeTextGenRequest(origRequest *chatCompletionRe
 					Type:  "tool_use",
 					Id:    tc.Id,
 					Name:  tc.Function.Name,
-					Input: inputMap,
+					Input: &inputMap,
 				})
 			}
 

plugins/wasm-go/extensions/ai-proxy/provider/claude_to_openai_test.go

@@ -383,6 +383,42 @@ func TestClaudeToOpenAIConverter_ConvertClaudeRequestToOpenAI(t *testing.T) {
 		assert.Equal(t, float64(5), args["max_results"])
 	})
 
+	t.Run("preserve_empty_tool_use_input", func(t *testing.T) {
+		claudeRequest := `{
+			"model": "anthropic/claude-sonnet-4",
+			"messages": [{
+				"role": "assistant",
+				"content": [{
+					"type": "thinking",
+					"thinking": "Need to list items.",
+					"signature": "sig"
+				}, {
+					"type": "tool_use",
+					"id": "toolu_empty",
+					"name": "list_items",
+					"input": {}
+				}]
+			}],
+			"max_tokens": 1000
+		}`
+
+		result, err := converter.ConvertClaudeRequestToOpenAI([]byte(claudeRequest))
+		require.NoError(t, err)
+		require.Contains(t, string(result), `"input":{}`)
+
+		var openaiRequest chatCompletionRequest
+		err = json.Unmarshal(result, &openaiRequest)
+		require.NoError(t, err)
+
+		require.Len(t, openaiRequest.Messages, 1)
+		assistantMsg := openaiRequest.Messages[0]
+		require.Len(t, assistantMsg.ToolCalls, 1)
+		assert.Equal(t, "{}", assistantMsg.ToolCalls[0].Function.Arguments)
+		require.Len(t, assistantMsg.ClaudeContentBlocks, 2)
+		require.NotNil(t, assistantMsg.ClaudeContentBlocks[1].Input)
+		assert.Empty(t, *assistantMsg.ClaudeContentBlocks[1].Input)
+	})
+
 	t.Run("convert_tool_result_to_tool_message", func(t *testing.T) {
 		// Test Claude tool_result conversion to OpenAI tool message format
 		claudeRequest := `{