We do not recommend adding names or credits into any metadata unless you have explicit permission to do so.
If necessary, you may include credits of people who worked on the content but are not visible in the image or video, like makeup artists, stylists, art directors, etc. Model names should NEVER be included, even if it's just a first name, in order to protect their privacy.
You may mention a brand name in metadata when it's relevant to the image, but do so with caution. For example, you can include a brand name for tech that is visible in any asset (iPhone, etc), but avoid creating any close association with a brand. For example, you can describe a prop as an Apple iPhone, but you shouldn’t say, "I shot this for Apple."
Please be aware that clients are not obligated to include any credits when they purchase and use your content, so your agreements with other artists should never be dependent on credit being included with published work.
When working with unique property such as designer clothing, art, performances, etc., a property release should be included.