The maximum request size for the Dialog API isn't explicitly stated in the documentation. However, it's important to note that the size of your request could impact the performance of the API. For instance, when you're working with the Knowledge Base API, the size of the document chunks you're working with can affect the speed of the response and the number of tokens consumed. The default chunk size is 1000 tokens, with a range of 500-1500 tokens available.
If you're encountering a "Request entity too large" error, it might be necessary to reduce the size of your request. This could involve sending smaller arrays of data or reducing the size of the individual elements within your array.
Please note that this is a general guidance and the exact limits might vary based on specific use cases and the structure of your data.