[DOCS] Environment variables page missing ANTHROPIC_CUSTOM_MODEL_OPTION env var

Documentation Type

Missing documentation (feature not documented)

Documentation Location

https://code.claude.com/docs/en/env-vars

Section/Topic

Environment variables reference table

Current Documentation

No documentation currently exists for ANTHROPIC_CUSTOM_MODEL_OPTION. The env-vars page has a comprehensive alphabetical table of environment variables, but this variable and its companion suffixed variants (_NAME, _DESCRIPTION) are absent. The model-config page documents model selection via the /model picker and modelOverrides setting but does not mention this env var.

What's Wrong or Missing?

Changelog v2.1.78 added the ANTHROPIC_CUSTOM_MODEL_OPTION environment variable to add a custom entry to the /model picker, with optional ANTHROPIC_CUSTOM_MODEL_OPTION_NAME and ANTHROPIC_CUSTOM_MODEL_OPTION_DESCRIPTION suffixed variants for display customization.

Users who want to add custom model options to the model picker (e.g., for proxied models, fine-tuned models, or internal deployments) cannot discover this feature from the documentation.

Suggested Improvement

Add entries to the env-vars table:

| Variable | Description |
|----------|-------------|
| ANTHROPIC_CUSTOM_MODEL_OPTION | Add a custom entry to the /model picker. Set to the model ID to use when this option is selected. |
| ANTHROPIC_CUSTOM_MODEL_OPTION_NAME | Display name for the custom model option in the /model picker. Optional; defaults to the model ID. |
| ANTHROPIC_CUSTOM_MODEL_OPTION_DESCRIPTION | Description text shown for the custom model option. Optional. |

Also add a cross-reference or example in the model-config page showing how to use these env vars to add custom model entries.

Impact

High - Prevents users from using a feature

Additional Context

Affected Pages:

| Page | Context |
|------|---------|
| https://code.claude.com/docs/en/env-vars | Environment variables reference table |
| https://code.claude.com/docs/en/model-config | Model selection and /model picker |

Total scope: 2 pages affected

Source: Changelog v2.1.78

Added ANTHROPIC_CUSTOM_MODEL_OPTION env var to add a custom entry to the /model picker, with optional _NAME and _DESCRIPTION suffixed vars for display