You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
Cloud ProvidersArea: what it touches
ImprovementsKind: in v2.1.284,
ImprovementsSection of the release
What
ANTHROPIC_FOUNDRY_RESOURCE is the environment variable that tells Claude Code which Microsoft Foundry resource to use when ANTHROPIC_FOUNDRY_BASE_URL is not set. An environment variable is a setting passed to a program from your shell.
The value must now be 2 to 64 letters, digits or hyphens, and it cannot start or end with a hyphen, for example my-resource.
Before, the value was dropped straight into https://<resource>.services.ai.azure.com. Now that address is built only from a valid name.
A value that is a URL or a host name now fails with an error that says to set ANTHROPIC_FOUNDRY_BASE_URL instead if you want to use a full URL.
A valid name is passed to the Foundry client explicitly as resource.
The runner's inference configuration rejects bad names with the same message.
Why
If you had put a full address in ANTHROPIC_FOUNDRY_RESOURCE, Claude Code now tells you plainly what is wrong instead of failing later with a confusing connection error. A malformed value can also no longer turn into a request to an unexpected host.
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeFixed ANTHROPIC_FOUNDRY_RESOURCE being interpolated into the Foundry endpoint host unvalidated; a value that is not a plain resource name is…
