The error message for unsupported full-PDF reading has been updated from "only supported with the Anthropic API" to "not supported with this model. Use a newer model (Sonnet 3.5 v2 or later)". This gives users clearer guidance on which models support the feature.
Evidence
Model-specific PDF error (search for "Reading full PDFs is not supported with this model")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.