ANTHROPIC_CUSTOM_MODEL_OPTION
A Claude Code environment variable, read out of the shipped bundle. It has been in the build since v2.1.138, including the newest one read.
What it is
Model ID to add as a custom entry in the /model picker. Use this to make a non-standard or gateway-specific model selectable without replacing built-in aliases. See [Model configuration](/docs/en/model-config#add-a-custom-model-option)
Anthropic's own wording. Read off Environment variables, captured 2026-08-28.
Presence across releases
| Releases | Reading | Declared type | Default |
|---|---|---|---|
| 2.1.245 – 2.1.250 5 releases | never mined | — | — |
| 2.1.160 – 2.1.243 75 releases | in the build | str | — |
| 2.1.138 – 2.1.159 20 releases | in the build | — | — |
A row reading never mined is a release with no archived bundle behind it. Nothing was read out of it, so nothing here says whether the name was in it. A declared type or a default is only ever what that release's own bundle stated.
Changelog entries naming it
-
v2.1.242New
modelPickersetting curates the /model listA new modelPicker setting curates or replaces the model list you see in /model.
named in this entry
Documentation pages
- Environment variables reference table Claude Code CLI
- Model configuration mentions it Claude Code CLI
- Claude Code settings reference mentions it Claude Code CLI
A reference table page is one whose own table defines this name, and it is where the description above came from. A page that mentions it carries the name somewhere in its text and may say nothing about it at all. Every page carrying it.
Names beside it
Every environment variable in the inventory starting anthropic_custom_model, up to twelve of them.
ANTHROPIC_CUSTOM_MODEL_OPTION_DESCRIPTIONDisplay description for the custom model entry in the /model picker. Defaults to Custom model (<model-id>) when not set 2.1.138
ANTHROPIC_CUSTOM_MODEL_OPTION_NAMEDisplay name for the custom model entry in the /model picker. Defaults to the model ID when not set 2.1.138
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the environment variable does. All environment variables.