Describe the useful visual information
Good alternative text communicates what matters in an image when the image cannot be seen. For a modelling portfolio that can include the model, framing, garment or product category, pose and relevant setting. It should not become a hidden paragraph stuffed with every city and modelling keyword imaginable.
A clean description such as a close beauty portrait or full-length fashion image is more useful than a filename or repeated generic phrase.
Accessibility and machine meaning can align
Descriptive image context helps assistive technology while also making a portfolio's visual categories easier for machines to interpret. Captions, nearby headings and structured image metadata can carry additional context that does not belong inside alt text.
The strongest implementation treats accessibility as information architecture rather than an SEO trick.