You have different obligations under different sections and acts. I'll give more info than you asked for in an effort to be thorough.
Under the Compulsory Automobile Insurance Act s. 4(1), you are obliged to disclose the particulars of your insurance in ANY collision that you are directly or indirectly involved in, on request of any person directly or indirectly involved in the collision.
Under s. 199 of the HTA, you are obliged to report any collision in which you are directly or indirectly involved to the police where there is over $1000 or there is any injury.
Under s. 200 of the HTA, you are obliged to give in writing to anyone sustaining loss or injury or to any police officer or to any witness his or her name, address, drivers licence number and jurisdiction of issuance, motor vehicle liability insurance policy insurer and policy number, name and address of the registered owner of the vehicle and the vehicle permit number (plate number).
Note that s. 200 applies to ANY collision, no matter how small, but the stipulation is that it only applies to "anyone sustaining loss or injury". It is up to you to determine if the other driver meets this criteria. You must also consider the possibility that, if you believe they have not sustained loss or injury, but in fact they have, and you fail to provide the required information, you may be charged under this section. However, since this is a strict liability offence, a defence of due diligence would be available to you in court, which means you could potentially excuse yourself from liability if you can show that you (a) took all reasonable steps to ascertain whether they were injured or suffered loss, or (b) had an honest belief in a mistaken set of facts which, if true, would have rendered your actions not an offence.