Carry and forward agent

If agent for buying or selling, then registration is mandatory without any limits. Goods have to be received through GST tax invoices, avail ITC and sell with output GST. If merely acting as agent for transport and handling of goods, then registration may not be required. 

Kindly refer below definition of agent, to see if you fit within the same or not : 

2 (5). "agent" means a person, including a factor, broker, commission agent, arhatia, del credere agent, an auctioneer or any other mercantile agent, by whatever name called, who carries on the business of supply or receipt of goods or services or both on behalf of another;

C&F agent is best example of Pure Agent.
In term of explaintion to rule 33 of CGST Act , pure agent means one who :
1. enter into contractual agreement with recipient .
2 he neither to hold nor holds any title to the goods or services procured or supplied as pure agent
3. Does not use the goods or services for his own interest.
4. receives only actual amount incurred to procure such goods.

Hence as per above the Pure Agent are not cover under the provisions of section 24 of mandatory registration.

Note : Pure agent is required to obtain the registration only if the aggregate turnover is exceeds as prescribed in section 22 of CGST Act.
so not mandatory to require to obtain registration if your aggregate turnover is below 20 lac .

Can refer circular 57/31/2018 GST