Environment Variables

The following environment variables are available in all agent bash tool executions, including init hooks.

Available Variables

Variable	Description
`MUX_PROJECT_PATH`	Absolute path to the project root on the local machine. Always refers to your local project path, even on SSH workspaces.
`MUX_RUNTIME`	Runtime type: `"local"`, `"worktree"`, `"ssh"`, or `"docker"`
`MUX_WORKSPACE_NAME`	Name of the workspace (typically the branch name)
`MUX_MODEL_STRING`	Model identifier (e.g., `"anthropic:claude-sonnet-4-20250514"`)
`MUX_THINKING_LEVEL`	Reasoning level: `"off"`, `"low"`, `"medium"`, `"high"`, or `"xhigh"`
`MUX_COSTS_USD`	Cumulative session costs in USD, formatted to 2 decimal places (e.g., `"1.23"`)

Usage Example

#!/usr/bin/env bash

echo "Project: $MUX_PROJECT_PATH"
echo "Runtime: $MUX_RUNTIME"
echo "Workspace: $MUX_WORKSPACE_NAME"
echo "Model: $MUX_MODEL_STRING"
echo "Thinking: $MUX_THINKING_LEVEL"
echo "Costs: \$${MUX_COSTS_USD:-0.00}"

# Runtime-specific behavior
if [ "$MUX_RUNTIME" = "ssh" ]; then
  echo "Running on SSH remote"
elif [ "$MUX_RUNTIME" = "docker" ]; then
  echo "Running in Docker container"
else
  echo "Running locally"
fi

Use Cases

PR footers: Include model and cost information in automated PR descriptions
Conditional logic: Adapt scripts based on runtime environment
Logging: Track which model and settings were used for a task
Cost monitoring: Check cumulative costs before expensive operations

​Available Variables

​Usage Example

​Use Cases

Available Variables

Usage Example

Use Cases