Discord.Net/docs/guides/concepts/ratelimits.md

Ratelimits

Ratelimits are a core concept of any API - Discords API is no exception. Each verified library must follow the ratelimit guidelines.

Using the ratelimit callback

There is a new property within RequestOptions called RatelimitCallback. This callback is called when a request is made via the rest api. The callback is called with a IRateLimitInfo parameter:

Name	Type	Description
IsGlobal	bool	Whether or not this ratelimit info is global.
Limit	int?	The number of requests that can be made.
Remaining	int?	The number of remaining requests that can be made.
RetryAfter	int?	The total time (in seconds) of when the current rate limit bucket will reset. Can have decimals to match previous millisecond ratelimit precision.
Reset	DateTimeOffset?	The time at which the rate limit resets.
ResetAfter	TimeSpan?	The absolute time when this ratelimit resets.
Bucket	string	A unique string denoting the rate limit being encountered (non-inclusive of major parameters in the route path).
Lag	TimeSpan?	The amount of lag for the request. This is used to denote the precise time of when the ratelimit expires.
Endpoint	string	The endpoint that this ratelimit info came from.

Let's set up a ratelimit callback that will print out the ratelimit info to the console.

public async Task MyRatelimitCallback(IRateLimitInfo info)
{
    Console.WriteLine($"{info.IsGlobal} {info.Limit} {info.Remaining} {info.RetryAfter} {info.Reset} {info.ResetAfter} {info.Bucket} {info.Lag} {info.Endpoint}");
}

Let's use this callback in a send message function

[Command("ping")]
public async Task ping()
{
    var options = new RequestOptions()
    {
        RatelimitCallback = MyRatelimitCallback
    };

    await Context.Channel.SendMessageAsync("Pong!", options: options);
}

Running this produces the following output:

False 5 4  2021-09-09 3:48:14 AM +00:00 00:00:05 a06de0de4a08126315431cc0c55ee3dc 00:00:00.9891364 channels/848511736872828929/messages