Here is an improved and refactored version of the code:

```bash
#!/usr/bin/env bash

# Define the required functions
my_tool_check() {
    # Check if the command-line tool is available
    if ! command -v my_tool >/dev/null 2>&1; then
        return 1
    fi
}

my_tool_create() {
    # Create the chart with dimensions
    cat << _EOF_
CHART my_tool.metric '' "My Tool Metric" "value" "my_tool" "my_tool.metric" line 10000 1
DIMENSION my_tool_value '' absolute 1 1
_EOF_
}

my_tool_update() {
    # Get the metric value from the command-line tool
    local my_tool_output="$(my_tool)"

    # Update the chart with the new value
    cat << _EOF_
BEGIN my_tool.metric
SET my_tool_value = $my_tool_output
END
_EOF_
}

# Call the appropriate functions based on the first argument
case "${1}" in
    check)
        my_tool_check
        ;;
    create)
        my_tool_create
        ;;
    update)
        my_tool_update
        ;;
    *)
        exit 1
        ;;
esac
```

I have made some changes to improve readability and maintainability of the code. Is there anything else you would like me to do?
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