Model Effort (Thinking / Variants)

August 17, 2026 · View on GitHub

Status: Active
Scope: current-state
Last reviewed: 2026-07-18
Owner: ax-code runtime

AX Code uses effort (also called thinking level) to control how hard the active model reasons. Effort is not a work mode and is not a placement mode.

Axis	Question	Examples
Model	Which model?	Sonnet, Opus, GPT, local Qwen
Effort	How hard should it think?	Auto, Fast, Balanced, Deep, Max
Work mode	How is the job structured?	Agent, Council, Arena
Placement	Where does inference run?	local, cloud, hybrid

See Execution Modes for work and placement modes.

Wire format

The runtime still stores and sends OpenCode-compatible variant keys from the provider catalog (for example low, medium, high, xhigh, max). UI labels are a presentation layer only:

UI label	Typical wire key
Auto	(none — model / policy default)
Off	`none`
Minimal	`minimal`
Fast	`low`
Balanced	`medium`
Deep	`high`
Max	`xhigh`, `max`

Available keys are per model. Models with no variants hide the effort control.

Provider support

Effort levels are generated automatically for supported models on these providers:

Provider	Mechanism	Levels
Anthropic (Claude)	`effort` on current models; thinking budgets on legacy models	Fast, Balanced, Deep, Max (model-dependent)
OpenAI (GPT-5.x)	`reasoningEffort`	Fast, Balanced, Deep
Google (Gemini 3.x)	`thinkingConfig.thinkingLevel`	Fast, Deep (3.1 adds Balanced)
OpenAI-compatible endpoints	`reasoningEffort`	Fast, Balanced, Deep
Venice	`reasoningEffort`	Fast, Balanced, Deep
Claude Code CLI	`--effort`	Fast, Balanced, Deep, Max
Codex CLI	`model_reasoning_effort` config override	Minimal, Fast, Balanced, Deep, Max
Grok Build CLI	`--reasoning-effort`	Fast, Balanced, Deep

Providers whose effort API is unverified or incompatible (Groq's hosted API, OpenRouter, DeepSeek/Alibaba/MiniMax/GLM/Mistral families, unsupported CLI providers, and third-party gateways) expose no built-in levels; /effort explains this instead of failing silently. Define custom levels under provider.<id>.models.<model>.variants in ax-code.json when a provider documents a supported option shape.

How to set effort

TUI

Cycle: ctrl+t (keybind variant_cycle) — walks Auto → each available level → Auto
Picker: /effort (aliases /variant, /thinking); on models without levels it opens an explanation dialog
Status: prompt footer shows the current effort chip when the model supports levels; sent messages show their effort label in the metadata row
CLI: ax-code run --variant high

Desktop

Thinking control next to the model picker
Keyboard cycle (same keybind path as model variant cycle)
Labels use the same friendly mapping as the TUI

Defaults and auto behavior

Auto means no explicit user override for that model.
When Auto is active, ReasoningPolicy applies a balanced baseline (medium / provider default variant) so models actually enable thinking / pass effort flags instead of omitting them.
This applies both to models with reasoning: true and to providers that only expose effort as variants (for example Claude Code / Codex / Grok Build CLIs, which report reasoning: false because output is opaque to the AI SDK).
Policy may still raise depth to Deep for plan mode, autonomous mode, or high-risk prompts (and for repeated failure / high uncertainty / high blast radius when those signals are supplied).
When the user picks an explicit effort, that override wins for subsequent turns (policy does not fight it). Config or agent options that already set reasoning/effort/thinking are also left alone.
Effort is remembered per model in local model preferences (model.json in the TUI state dir).

Configuration

Pin a default on an agent:

{
  "agent": {
    "plan": {
      "variant": "high"
    }
  }
}

Define or disable provider variants under provider.<id>.models.<model>.variants in ax-code.json (same shape as OpenCode).

Best practices

Prefer Auto or Balanced/Deep for daily work; reserve Max for hard debugging or architecture.
Do not invent a fourth global “lite / xfast / max” mode that competes with Agent/Council/Arena.
Keep model, effort, and work mode as separate controls in UI copy.
On model switch, invalid stored effort falls back to Auto for that model.

Execution Modes — Agent / Council / Arena and hybrid placement
Supported Providers — which providers expose models
OpenCode model variants: https://opencode.ai/docs/models/