It's an excessive theory for an idea this simple, but "honest signaling" is a hell of an insight. If anyone who wants a job can send a given signal, it's a poor signal. If only people with a certain trait can send it, it's a good one - hence personality interviews for communication, hence technical interviews for programming languages.

"Show don't tell" is a pretty basic (but incredibly important) writing concept that many people never learn.

Contrarian opinion:

Saying "I'm a good communicator" is the most succinct and clear way of communicating that one is a good communicator.

The recipient needs only read 4 words to get the message.

But what about the three-word sentence "I communicate well"?

More seriously, the most that reading "I'm a good communicator" tells me is that the writer can form sentences reasonably.

Succinct? Sure, but it's still so broad. When I'm working with someone, I would appreciate a troubleshooting message of "The Flob server is saying clients don't have the right Gruffin anymore." instead of "Flob isn't working."

Obviously this depends on context, but choosing where to be succinct is key. My project manager would much rather hear "Flob is down for half the users - we'll have a patch tested and deployed by tomorrow afternoon" than "Flob broke, and we're fixing it".

"I have a proven history of writing clear and efficient end-user documentation" and "I'm someone people enjoy bouncing ideas off of" give me more confidence in someone's communication skills than "I'm a good communicator".

The problem is that perhaps 75% of the people who say it are incorrect. There are a handful of trite items on a high percentage of resumes (team player, communicator, able to work in high pressure, etc.) that are virtually ignored - nobody has ever brought someone in for interview because they wrote "I'm a good communicator".

Generally I'll assume you're a good communicator until you show otherwise.