Rate limits · Pipsocket docs

Pipsocket doesn't limit how many requests a key makes. What it does limit is how much can wait at once, so one slow call can't hold up the rest:

Limit	Where	When it's reached
5 seconds for the trade server's answer	Each trade call	`202` with `"state": "pending"`: the request goes on without you.
30 seconds for the host's answer	Each REST call	`504 engine_timeout`.
16 calls waiting for their answer	Each stream	`{ "type": "error", "error": "too_many_calls" }`; send more as answers arrive.
100 symbols with ticks	Each account, all its streams together	`422 too_many_symbols` on `PUT /ticks`.
256 calls at once	Each host, all its accounts together	`503 engine_busy`: try again.
1,000 trades waiting for the trade server	Each account's terminal	The request is `refused` with `busy`.

Your broker has limits of its own. MT5 answers them as retcodes, such as 10024 (TRADE_RETCODE_TOO_MANY_REQUESTS), 10033 (pending orders) and 10040 (open positions): see retcodes.