Anthropic | Messages

Send a structured list of input messages with text content, and the model will generate the next message in the conversation.

Simple Example

Send a Hello message to Claude.

Anthropic := TsgcHTTP_API_Anthropic.Create(nil);
Anthropic.AnthropicOptions.ApiKey := 'API_KEY';
WriteLn(Anthropic._CreateMessage('claude-sonnet-4-20250514', 'Hello!'));

System Prompt Example

Send a message with a system prompt to control Claude's behavior.

Anthropic := TsgcHTTP_API_Anthropic.Create(nil);
Anthropic.AnthropicOptions.ApiKey := 'API_KEY';
WriteLn(Anthropic._CreateMessageWithSystem('claude-sonnet-4-20250514',
  'You are a helpful assistant that responds in Spanish.',
  'What is the capital of France?'));

Advanced Example

Use the typed request/response classes for full control over message parameters.

Anthropic := TsgcHTTP_API_Anthropic.Create(nil);
Anthropic.AnthropicOptions.ApiKey := 'API_KEY';

oRequest := TsgcAnthropicClass_Request_Messages.Create;
Try
  oRequest.Model := 'claude-sonnet-4-20250514';
  oRequest.MaxTokens := 1024;
  oRequest.System := 'You are a helpful assistant.';
  oRequest.Temperature := 0.7;

  oMessage := TsgcAnthropicClass_Request_Message.Create;
  oMessage.Role := 'user';
  oMessage.Content := 'Hello!';
  oMessages := oRequest.Messages;
  SetLength(oMessages, 1);
  oMessages[0] := oMessage;
  oRequest.Messages := oMessages;

  oResponse := Anthropic.CreateMessage(oRequest);
  Try
    if Length(oResponse.Content) > 0 then
      WriteLn(oResponse.Content[0].Text);
  Finally
    oResponse.Free;
  End;
Finally
  oMessage.Free;
  oRequest.Free;
End;

Streaming Example

Use Server-Sent Events (SSE) to stream the response in real-time. Assign the OnHTTPAPISSE event handler to receive streaming events.

Anthropic := TsgcHTTP_API_Anthropic.Create(nil);
Anthropic.AnthropicOptions.ApiKey := 'API_KEY';
Anthropic.OnHTTPAPISSE := OnSSEEvent;
Anthropic._CreateMessageStream('claude-sonnet-4-20250514', 'Tell me a story.');

procedure TForm1.OnSSEEvent(Sender: TObject; const aEvent, aData: string;
  var Cancel: Boolean);
begin
  // aEvent contains the event type (e.g. content_block_delta)
  // aData contains the JSON data for this event
  Memo1.Lines.Add(aData);
end;