Log output from mcp installer script as json-rpc (#6757)

Co-authored-by: Ben Broderick Phillips <bebroder@microsoft.com>

eng/common/mcp/azure-sdk-mcp.ps1

@@ -20,6 +20,54 @@ $ErrorActionPreference = "Stop"
 
 $toolInstallDirectory = $InstallDirectory ? $InstallDirectory : (Get-CommonInstallDirectory)
 
+$mcpMode = $Run
+
+# Log to console or MCP client json-rpc
+function log([object]$message, [switch]$warn, [switch]$err) {
+    [string]$messageString = $message
+
+    # Assume we are in an MCP client context when `-Run` is specified
+    # otherwise print to console normally
+    if (!$mcpMode) {
+        if ($err) {
+            Write-Error $messageString -ErrorAction Continue
+        }
+        elseif ($warn) {
+            Write-Warning $messageString
+        }
+        else {
+            Write-Host $messageString
+        }
+        return;
+    }
+
+    $level = switch ($message) {
+        { $_ -is [System.Management.Automation.ErrorRecord] } { 'error' }
+        { $_ -is [System.Management.Automation.WarningRecord] } { 'warning' }
+        default { 'notice' }
+    }
+
+    # If message stringifies as a valid error message we want to print it
+    # otherwise print stack for calls to external binaries
+    if ($messageString -eq 'System.Management.Automation.RemoteException') {
+        $messageString = $message.ScriptStackTrace
+    }
+
+    # Log json-rpc messages so the MCP client doesn't print
+    # '[warning] Failed to parse message:'
+    $messageObject = @{
+        jsonrpc = "2.0"
+        method  = "notifications/message"
+        params  = @{
+            level  = $level
+            logger = "installer"
+            data   = $messageString
+        }
+    }
+
+    Write-Host ($messageObject | ConvertTo-Json -Depth 100 -Compress)
+}
+
 if ($UpdateVsCodeConfig) {
     $vscodeConfigPath = Join-Path $PSScriptRoot ".." ".." ".." ".vscode" "mcp.json"
     if (Test-Path $vscodeConfigPath) {
@@ -45,7 +93,7 @@ if ($UpdateVsCodeConfig) {
         }
     }
     $vscodeConfig.servers = $orderedServers
-    Write-Host "Updating vscode mcp config at $vscodeConfigPath"
+    log "Updating vscode mcp config at $vscodeConfigPath"
     $vscodeConfig | ConvertTo-Json -Depth 10 | Set-Content -Path $vscodeConfigPath -Force
 }
 
@@ -54,12 +102,36 @@ if ($UpdateVsCodeConfig) {
 $tmp = $env:TEMP ? $env:TEMP : [System.IO.Path]::GetTempPath()
 $guid = [System.Guid]::NewGuid()
 $tempInstallDirectory = Join-Path $tmp "azsdk-install-$($guid)"
-$tempExe = Install-Standalone-Tool `
-    -Version $Version `
-    -FileName $FileName `
-    -Package $Package `
-    -Directory $tempInstallDirectory `
-    -Repository $Repository
+
+if ($mcpMode) {
+    try {
+        # Swallow all output and re-log so we can wrap any
+        # output from the inner function as json-rpc
+        $tempExe = Install-Standalone-Tool `
+            -Version $Version `
+            -FileName $FileName `
+            -Package $Package `
+            -Directory $tempInstallDirectory `
+            -Repository $Repository `
+            *>&1
+        | Tee-Object -Variable _
+        | ForEach-Object { log $_; $_ }
+        | Select-Object -Last 1
+    }
+    catch {
+        log -err $_
+        exit 1
+    }
+}
+else {
+    $tempExe = Install-Standalone-Tool `
+        -Version $Version `
+        -FileName $FileName `
+        -Package $Package `
+        -Directory $tempInstallDirectory `
+        -Repository $Repository `
+
+}
 
 if (-not (Test-Path $toolInstallDirectory)) {
     New-Item -ItemType Directory -Path $toolInstallDirectory -Force | Out-Null
@@ -68,12 +140,13 @@ $exeName = Split-Path $tempExe -Leaf
 $exeDestination = Join-Path $toolInstallDirectory $exeName
 Copy-Item -Path $tempExe -Destination $exeDestination -Force
 
-Write-Host "Package $package is installed at $exeDestination"
+log "Package $package is installed at $exeDestination"
 if (!$UpdatePathInProfile) {
-    Write-Warning "To add the tool to PATH for new shell sessions, re-run with -UpdatePathInProfile to modify the shell profile file."
-} else {
+    log -warn "To add the tool to PATH for new shell sessions, re-run with -UpdatePathInProfile to modify the shell profile file."
+}
+else {
     Add-InstallDirectoryToPathInProfile -InstallDirectory $toolInstallDirectory
-    Write-Warning "'$exeName' will be available in PATH for new shell sessions."
+    log -warn "'$exeName' will be available in PATH for new shell sessions."
 }
 
 if ($Run) {