[FEATURE] Add effort parameter support for Opus 4.5 in Claude Code

[mehulparmariitr]

Preflight Checklist

• I have searched existing requests and this feature hasn't been requested yet
• This is a single feature request (not multiple features)

Problem Statement

Problem Statement

Opus 4.5 introduced an effort parameter (low/medium/high) via the API that controls token usage and response thoroughness. This is currently not exposed in Claude Code CLI.

Proposed Solution

Proposed Solution

Add ability to configure the effort level via:

• Environment variable: CLAUDE_CODE_EFFORT=medium
• Settings file: ~/.claude/settings.json with "effort": "medium"
• CLI flag: claude --effort medium
• Slash command: /effort medium

Use Case

• Use low for simple tasks, faster responses
• Use medium for balanced performance (76% fewer tokens than Sonnet)
• Use high (default) for complex reasoning tasks

References

• Effort parameter docs
• Opus 4.5 announcement

Alternative Solutions

No response

Priority

High - Significant impact on productivity

Feature Category

CLI commands and flags

Use Case Example

No response

Additional Context

No response

[mehulparmariitr]

Whats the default effort for claude code Opus 4.5?

[trevorprater]

It defaults to 'high' and it's already supported via environment variable, it's just not documented.

[mehulparmariitr]

It defaults to 'high' and it's already supported via environment variable, it's just not documented.

Which env variable, please share the details.

[Majdoddin]

any updates?

[mooneydude]

It defaults to 'high' and it's already supported via environment variable, it's just not documented.

are you also setting header via environment var as per claude api docs. if so, how?

--header "anthropic-beta: effort-2025-11-24"

or

betas=["effort-2025-11-24"],

[nightpool]

Also curious about this. #12403 mentions that the env var doesn't work anymore.

[BarsMonster]

Can confirm that old env variable (CLAUDE_CODE_EFFORT_LEVEL) is broken.

[github-actions]

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