Models
Use any model with Letta Code
Letta Code is model-agnostic. Agents can use Claude, GPT, Gemini, or other supported models. Users can change an agent’s underlying model at any time, even mid-conversation.
Switching models
Section titled “Switching models”Use the /model command to switch models during a session:
> /modelThis opens a model selector with two categories:
- Supported - Pre-configured models with optimized settings
- All Available - All models available on your account, including custom BYOK (Bring Your Own Key) models
Use Tab to switch categories, arrow keys to navigate, and j/k to change pages.
You can also specify a model when starting Letta Code:
letta --model gpt-5-codexletta -m haikuToolsets
Section titled “Toolsets”Different models are trained to work best with different tools. For example, GPT-5 models are trained to use a patch-based editing tool, while Claude models work better with string-based edit tools.
Letta Code handles this automatically with toolsets - optimized tool configurations for each model family. When you switch models with /model, Letta Code automatically switches to the optimal toolset.
| Toolset | Optimized for |
|---|---|
| Default | Claude models (Anthropic) |
| Codex | GPT models (OpenAI) |
| Gemini | Google models |
Default toolset (Claude)
Section titled “Default toolset (Claude)”The default toolset is optimized for Anthropic models (Claude Sonnet, Opus, Haiku).
| Category | Tools |
|---|---|
| File editing | Edit (string-replace), Write |
| File reading | Read, Glob |
| Shell | Bash |
| Search | Grep (ripgrep-based) |
| Planning | EnterPlanMode, ExitPlanMode, TodoWrite |
| Agent features | Task (subagents), Skill (invoke skills), AskUserQuestion |
Codex toolset (OpenAI)
Section titled “Codex toolset (OpenAI)”The Codex toolset is optimized for OpenAI models (GPT-5, GPT-5-Codex). Uses patch-based editing instead of string-replace.
| Category | Tools |
|---|---|
| File editing | ApplyPatch (unified patch-based edit and write) |
| File reading | ReadFile, ListDir, view_image |
| Shell | ShellCommand, Shell |
| Search | GrepFiles |
| Planning | EnterPlanMode, ExitPlanMode, UpdatePlan |
| Agent features | Task (subagents), Skill (invoke skills), AskUserQuestion |
Gemini toolset (Google)
Section titled “Gemini toolset (Google)”The Gemini toolset is optimized for Google models (Gemini Pro, Flash).
| Category | Tools |
|---|---|
| File editing | Replace (string-replace), WriteFileGemini |
| File reading | ReadFileGemini, ReadManyFiles, ListDirectory, GlobGemini |
| Shell | RunShellCommand |
| Search | SearchFileContent |
| Planning | EnterPlanMode, ExitPlanMode, WriteTodos |
| Agent features | Task (subagents), Skill (invoke skills), AskUserQuestion |
Memory tools
Section titled “Memory tools”In addition to the client-side tools above, every Letta Code agent has a server-side memory tool for editing its memory blocks. The memory tool is automatically selected based on the model:
- Claude and Gemini models:
memory- an omni-tool with subcommands (create, view, str_replace, insert, delete, rename) - OpenAI models:
memory_apply_patch- patch-based memory editing
When you switch models with /model, the memory tool is swapped automatically.
Manual toolset override
Section titled “Manual toolset override”If you want to force a specific toolset:
letta --toolset codex> /toolset