Writer's Fallout Shelter

Yes, it is worth it.

I plan to look for an agent before I look for a publisher for my manuscript.

Agents know who is looking for what, know who to target with a particular manuscript, and can move your manuscript to the head of the line to be read. They also help negotiate contracts to get the writer a better deal.

That said, you should never, ever pay an upfront fee to an agent. If an agent is charging you fees to make you their client, then they are a scam. Run away. Fast.

Agents work on commission. They will take a percentage the advance and royalties for the job they do, which means the better deal they get for you, the more money they earn. That is their incentive.