Responses API, function calling example. #647

dmkdesign · 2025-08-16T01:18:38Z

dmkdesign
Aug 16, 2025

Hi guys,
I have been banging my head against the wall here trying to get function calls to work in streaming mode.

I keep getting "No tool call found for function call output with call_id call_sRySPrMxTPLe43ZahK6DrobZ"

My tools definition is:

$tools = [
        [
            'type' => 'function',
            'name' => 'website_text',
            'description' => 'retrieve the content of up to 5 pages selected by a sub-agent based on the client question',

            'tool_id' => 'website_tool_v1'
        ],
        [
            'type' => 'function',
            'name' => 'existing_seo_keywords',
            'description' => 'retrieve a list of keywords that the client\'s website is currently ranking in the top 100 for',

        ],
 ];

This is is getting called when i use it like:

$openAiParams = [
                'previous_response_id' => $this->getLastResponseId(),
                'instructions'=>$this->answer_prompt,
                'model' => $this->model,
                'temperature' => (float) $this->temperature,
                'tools' => $tools,
                'tool_choice' => 'auto',
                'parallel_tool_calls' => true,
                'store' => true,
                'input' => $messages,
            ];
            $stream  = $this->client->responses()->createStreamed($openAiParams);

Which I then process like:

foreach($stream as $event){
                    //var_dump($chunk);
                    //if this is empty then its the last chunk that has usage details.

                    switch($event['event'])
                    {
                        case 'response.output_text.delta':
                            echo "event: message\n";
                            $data = $event->response['delta'];
                            $data = nl2br($data);
                            echo "data: ".$data."\n\n";
                            flush();
                            break;
                        case 'response.output_text.done':
                            //if an image was generated then we append to final output
                            if(!empty($imageData))
                            {
                                echo "event: message\n";
                                echo "data: ".$imageData."\n\n";
                                flush();
                            }

                            break;
                        case 'response.image_generation_call.partial_image':
                            echo "event: status\n";
                            $imageData = Html::img('data:image/png;base64,'.$event->response['partial_image_b64'],['style'=>'width:100%']);
                            echo "data: Generating Image!<br>".$imageData."\n\n";
                            flush();
                            break;
                        case 'response.output_item.added':
                                                        
                            $delta = $event->response['item'];
                            echo "event: status\n";
                            echo "data: ".$delta['type']."!\n\n";
                            flush();
                            // // echo "event: message\n";
                            // // echo "data: ".json_encode($delta)."\n\n";
                            // // flush();
                            if($delta['type'] === 'function_call')
                            {
                                echo "event: message\n";
                                echo "data: Calling Tool".$delta['name']."\n\n";
                                flush();

                                // tool_call_id is unique per call
                                if (!isset($toolCalls[$event->response['output_index']])) {
                                    $toolCalls[$event->response['output_index']] = $delta;
                                }
                                
                            }
                            break;
                        case 'response.function_call_arguments.delta':
                            if(!empty($toolCalls[$event->response['output_index']])) {
                                    $toolCalls[$event->response['output_index']]['arguments'] .= $event->response['delta'];
                                }
                            break;
                        case 'response.completed':

                            $tokens = json_encode($event->response['usage']);
                            $responseData = $event->response['output']; //we should check type
                            //
                            $this->previous_response_id = $event->response['id'];
                            foreach($responseData as $output)
                            {
                                if(!empty($output['content']) )
                                {
                                    foreach($output['content'] as $content)
                                    {
                                        if($content['type']=='output_text')
                                        {
                                            if(!empty($content['text']))
                                                $returnString .= $content['text'].PHP_EOL;
                                        }
                                    }
                                }
                                    
                                
                                if($output['type']=='imagegenerationcall')
                                {
                                    $imageData .= Html::img('data:image/png;base64,'.$output['result'])."<br>";
                                }
                            }
                            $returnString .= $imageData;
                            $completed = true;
                            // //clean up files for now
                            // foreach( $this->savedFiles as $fileHandle)
                            // {
                            //     $this->client->files()->delete($fileHandle);
                            // }
                            break;
                        
                    }

                    if($completed)
                        break;
            
                }

This leaves me with toolCalls to process and then get the outputs

                foreach ($toolCalls as $call) {
                    // echo "Tool call detected:\n";
                    // echo "- Tool Call ID: {$call['tool_call_id']}\n";
                    // echo "- Tool ID: " . ($call['tool_id'] ?: 'none') . "\n";
                    // echo "- Name: {$call['name']}\n";
                    // echo "- Args JSON: {$call['arguments']}\n";
                    $args = null;
                    if(!empty($call['arguments']))
                    {
                        $args = json_decode($call['arguments'], true);
                    }
                    
                    if (json_last_error() !== JSON_ERROR_NONE) {
                        $result = ['error' => 'Invalid JSON arguments'];
                    } else {
                        // Simulate tool execution
                        try
                        {
                             $result = $this->executeTool($call['name'],$args);
                             //print_r($result);
                        }
                        catch(\Throwable $e)
                        {
                            $result = $e->getMessage();
                        }
                       
                    }

                    $toolMessages[] = [
                        'type'=> 'function_call_output',
                        'call_id' => $call['call_id'],
                        'output'=> json_encode(['result'=>$result]),
                    ];

And then I pass the tool data back to the responses API.

                    foreach($toolMessages as $toolResult)
                    {
                        $messages[] = $toolResult;
                    }
                    print_r($messages);
                    $openAiParams = [
                        'model' => $this->model,
                        //'previous_response_id' =>$this->previous_response_id ,
                        'temperature' => (float) $this->temperature,
                        'tools'=>$tools,
                        'input' => $messages,
                        
                    ];

                    $stream  = $this->client->responses()->createStreamed($openAiParams);

that call always throws an error about "No tool call found for function call output with call_id call_XXXXXXXXXXXXXXXXXXXXXXXX" but I have inspected the input $messages and it looks correct. Is there a special key I should be associating the function call data too?

thomaspapanikolaou · 2025-08-16T04:01:55Z

thomaspapanikolaou
Aug 16, 2025

I believe you have to pass not only the results, but also the $call to $toolMessages as in

$toolMessages[] = $call;
$toolMessages[] = [ 'type'=> 'function_call_output', 'call_id' => $call['call_id'], 'output'=> json_encode(['result'=>$result]), ];

This way the $call generated by the model can be found.

1 reply

dmkdesign Aug 16, 2025
Author

Hi Thomas,
Thanks for your reply.

That definitely got me on the path to fixing it! Couple other dumb moves cleared up and it seems like its working! Thanks a tonne.

thomaspapanikolaou · 2025-08-16T05:49:57Z

thomaspapanikolaou
Aug 16, 2025

If you are using previous_response_id in the 2nd replay call you just need to supply $toolMessages as input, as the $messages are already stored by OpenAI.

$openAiParams = [ 'model' => $this->model, 'previous_response_id' =>$this->previous_response_id , 'temperature' => (float) $this->temperature, 'input' => $toolMessages, ];

If you are not using previous_response_id do

$input = array_merge($messages, $toolMessages);
$openAiParams = [ 'model' => $this->model, 'input' => $messages, ];

You also don't need to add tools in the replay, unless you expect them to be called, and have another replay code to handle them.

1 reply

dmkdesign Aug 16, 2025
Author

That works well!

Thanks again for your input!

I created an issue by using the response_id from the first tool call. That will create the issue of having duplicate function calls in the input.

If I used the response_id from a truly previous call it works great and retains the tool data.

dmkdesign · 2025-08-17T04:23:59Z

dmkdesign
Aug 17, 2025
Author

Hoping to pick brains again. I've tried to move to GPT5 because 4o refuses to run multiple tool calls with built in functions like "web_search". GPT-5 calls them properly but when I try to use the same inputs into the second call I get an error about the reasoning not being found for a function call.

Item fc_XXXXXX of type 'functioncall' was provided without its required 'reasoning' item rs_xxxxxxxxx:

I've tried providing the reasoning item along with the inputs but to no avail in multiple different ways. Anyone seen this? How do I add the reasoning properly?

1 reply

dmkdesign Aug 19, 2025
Author

I've abandined the parallel tool call id. I now iterate through multiple responses and feed the tool results in until no more tool calls are present in the response. I believe there is a bug in parallel tool processing for reasoning models. One reasoning item is returned but each function call expects a reasoning item associated to it and they don't exist. I don't see how you can associate a single reasoning item with multiple function_call_items.

Uh oh!

Responses API, function calling example. #647

Uh oh!

Uh oh!

dmkdesign Aug 16, 2025

Replies: 3 comments · 3 replies

Uh oh!

Uh oh!

thomaspapanikolaou Aug 16, 2025

Uh oh!

Uh oh!

dmkdesign Aug 16, 2025 Author

Uh oh!

thomaspapanikolaou Aug 16, 2025

Uh oh!

dmkdesign Aug 16, 2025 Author

Uh oh!

Uh oh!

dmkdesign Aug 17, 2025 Author

Uh oh!

dmkdesign Aug 19, 2025 Author

dmkdesign
Aug 16, 2025

Replies: 3 comments 3 replies

thomaspapanikolaou
Aug 16, 2025

dmkdesign Aug 16, 2025
Author

thomaspapanikolaou
Aug 16, 2025

dmkdesign Aug 16, 2025
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dmkdesign
Aug 17, 2025
Author

dmkdesign Aug 19, 2025
Author