What is the correct way to reference a boolean parameter in SSM document for powershell?

I am trying to create an SSM document that deals with parameters but I am getting

Here is my Parameter block :

        "createfoo":{
            "type": "Boolean",
            "description": "Do you want to Create foo",
            "default": false
        }

Here is my runCommand block :

        "mainSteps": [
            {
                "action": "aws:runPowerShellScript",
                "name": "InstallGAIN",
                "inputs":{
                    "runCommand": [ 
                        "[bool] $createfoo={{createfoo}}",
                        "if ($createfoo -eq $true) {",
                        "Write-Host \"Creating foo\"",
                         "}"

] } ]

Update-SSMDocument : Parameter "createfoo" is "BOOLEAN" type and can't be used as a substring parameter. At line:2 char:21

$latestDocVersion = Update-SSMDocument

CategoryInfo : InvalidOperation: (Amazon.PowerShe...MDocumentCmdlet:UpdateSSMDo
cumentCmdlet) [Update-SSMDocument], InvalidOperationException + FullyQualifiedErrorId : Amazon.SimpleSystemsManagement.Model.InvalidDocumentContentExcep
tion,Amazon.PowerShell.Cmdlets.SSM.UpdateSSMDocumentCmdlet

Following is the command that I run to update my doc

$content = Get-Content -Path "installFoo.ssm" | Out-String
$latestDocVersion = Update-SSMDocument `
    -Content $content `
    -Name "installFoo" `
    -DocumentFormat "JSON" `
    -DocumentVersion '$LATEST' `
    | Select-Object -ExpandProperty LatestVersion

Update-SSMDocumentDefaultVersion `
    -Name "installFoo" `
    -DocumentVersion $latestDocVersion

Solution

I was able to do this by passing True/False value as string as suggested in comments by mklment0. Here is how paramater block looks like no :

        "createfoo":{
            "type": "String",
            "description": "Do you want to Create foo",
            "default": "false"
        }

Also the runCommand block :

        "mainSteps": [
            {
                "action": "aws:runPowerShellScript",
                "name": "InstallGAIN",
                "inputs":{
                    "runCommand": [ 
                        "if ({{createFoo}} -eq 'true') {",
                        "Write-Host \"Creating foo\"",
                         "}"

] } ]