I didn't work through an agency, I have been the founder of more than one consultancy. I had my own MSA/RSA agreements and SOW templates I would work from. And in some cases large companies or publicly traded ones would want to use their own contract and I would send them my requests which is part of normal business practices. If you don't send them back something on the contract than you probably haven't looked close enough to find the potential problems with it, and they get it. Any client that got all pissy about contract revisions was a client not worth having because they were trying to get something over on me and I wouldn't put up with it. Push back/negotiation is fine, pissy attitude isn't.

I am not a lawyer but use them when needed, you should too. But in general, usually in the MSA/RSA or similar I'd have a clause under a section called "publicity" or similar that would read substantially similar to below, where Company was my company and Client was the client we were doing work for:

"Notwithstanding anything to the contrary in the Agreement or applicable Statements of Work, Company shall be permitted to disclose in summary form the nature of the work performed for Client under the applicable Statement of Work. Such disclosure includes a description of the technology utilized by Company, but Company shall not disclose the proprietary business processes of Client or otherwise result in any breach of any other term of this Agreement."