One important thing to note is that often, when you leave a company, they will offer you a severance package in return for signing an agreement. This may happen if you are fired, or also if you leave on your own accord.
IANAL, but I've dealt with this situation and my key takeaways are as follows:
1. Pay a lawyer to read the document for you and provide advice.
2. There are major differences in state law, and jurisdiction is important. For example, if you worked for Google in NY[0], and your contract was a NY-based contract, and there was a harsh noncompete in it[1], and you subsequently took a job in California that violated the terms of the non-compete, it doesn't matter that your new job is in California and Google's HQ is in California and Alphabet is domiciled in Delaware. You signed, and are potentially in violation of, a contract whose potential violation would be adjudicated in New York.
3. Upon receiving advice from your lawyer, and bearing in mind the importance of state jurisdiction, ask your former employer to make changes to the agreement as you see fit, especially if there is an aggressively worded non-compete.
4. Don't believe them when they say "this is just a formality". Read the fine print and understand what it means.
[0]: Has already been mentioned a couple times in this thread, but California is a much more employee-friendly state than NY. Non-competes are essentially unenforceable, as are non-poach agreements. It's my understanding that disparagement clauses are also a lot harder to enforce in CA, but IANAL.
[1]: To be clear, I am not sure whether this would be the case at Google specifically, just using a well-known California-based company as an example.
The "just a formality" line really bugs me. I once contracted for a place that asked me to indemnify them against all fines or taxes due against them in relation to my contract with them. So, I asked them to amend it to include language that excluded cases where they are informed that they are breaking the law, where they agree to a settlement with a third party, where they refuse to defend an action, where they fail to notify me immediately after an accusation is made, etc. They refused, saying it's just a formality.
I can understand why their lawyers were keen on having people sign it, as they were so clearly abusing their relationships with contractors, but I don't understand why so many of my colleagues did.
I was told a clause was unenforceable, and used the reasoning "So we can remove it from the contract?" and they wanted me to work with them so they took it out.
My usual approach with NCs is to reign in the scope of them. I've had some that could be interpreted I couldn't write any software for anyone else for up to a year.
Companies have a way of shitting their pants, and walking away from the employment offer if you question even a line or two of the "formalities" they expect you to unblinkingly sign.
True but it grinds the gears nonetheless (especially when considerable time has been invested, and you were actually kind of interested in what they were doing).
Worth noting that in the UK it is pretty standard for your employer to pay for your lawyer (not their lawyer) to review your "compromise agreement" - there is a standard fee of £500 or so for this which a decent employment lawyer will be able to get a decent amount of work done even if their hourly rate is much higher.
I left my previous employer a couple of years ago and it ended up with a fair bit of negotiation and it was all covered under the standard fee. The particularly nice thing is that they bill your employer, not you!
I remember a place that asked me to sign a "exit agreement" with all sorts of ridiculous things on it, but did not offer a severance or any other kind of incentive for me to sign it. Had a good chuckle at that one. They insisted I couldn't leave until I signed it, and looked kind of confused when I said how about I just not come in the next day, or the day after, etc. They asked that they get some time to figure out how they were going to deal with that scenario...
IANAL, but I've dealt with this situation and my key takeaways are as follows:
1. Pay a lawyer to read the document for you and provide advice.
2. There are major differences in state law, and jurisdiction is important. For example, if you worked for Google in NY[0], and your contract was a NY-based contract, and there was a harsh noncompete in it[1], and you subsequently took a job in California that violated the terms of the non-compete, it doesn't matter that your new job is in California and Google's HQ is in California and Alphabet is domiciled in Delaware. You signed, and are potentially in violation of, a contract whose potential violation would be adjudicated in New York.
3. Upon receiving advice from your lawyer, and bearing in mind the importance of state jurisdiction, ask your former employer to make changes to the agreement as you see fit, especially if there is an aggressively worded non-compete.
4. Don't believe them when they say "this is just a formality". Read the fine print and understand what it means.
[0]: Has already been mentioned a couple times in this thread, but California is a much more employee-friendly state than NY. Non-competes are essentially unenforceable, as are non-poach agreements. It's my understanding that disparagement clauses are also a lot harder to enforce in CA, but IANAL.
[1]: To be clear, I am not sure whether this would be the case at Google specifically, just using a well-known California-based company as an example.