diff --git a/.phpstan-baseline.php b/.phpstan-baseline.php
index 484d5a7c550..52fa890dd9f 100644
--- a/.phpstan-baseline.php
+++ b/.phpstan-baseline.php
@@ -1999,18 +1999,6 @@
 	'count' => 1,
 	'path' => __DIR__ . '/src/GLPINetwork.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Call to function is_string\\(\\) with string will always evaluate to true\\.$#',
-	'identifier' => 'function.alreadyNarrowedType',
-	'count' => 1,
-	'path' => __DIR__ . '/src/Glpi/Agent/Communication/AbstractRequest.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Property Glpi\\\\Agent\\\\Communication\\\\AbstractRequest\\:\\:\\$response \\(DOMDocument\\) does not accept array\\.$#',
-	'identifier' => 'assign.propertyType',
-	'count' => 1,
-	'path' => __DIR__ . '/src/Glpi/Agent/Communication/AbstractRequest.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Dead catch \\- Glpi\\\\Exception\\\\PasswordTooWeakException is never thrown in the try block\\.$#',
 	'identifier' => 'catch.neverThrown',
@@ -3505,12 +3493,6 @@
 	'count' => 2,
 	'path' => __DIR__ . '/src/Glpi/Inventory/Inventory.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Call to function is_array\\(\\) with array will always evaluate to true\\.$#',
-	'identifier' => 'function.alreadyNarrowedType',
-	'count' => 1,
-	'path' => __DIR__ . '/src/Glpi/Inventory/Request.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Call to function in_array\\(\\) with arguments null, array\\{\'development\', \'testing\'\\} and true will always evaluate to false\\.$#',
 	'identifier' => 'function.impossibleType',
diff --git a/phpunit/functional/Glpi/Inventory/RequestTest.php b/phpunit/functional/Glpi/Inventory/RequestTest.php
index 82840af6a55..44aa29a575a 100644
--- a/phpunit/functional/Glpi/Inventory/RequestTest.php
+++ b/phpunit/functional/Glpi/Inventory/RequestTest.php
@@ -109,8 +109,12 @@ public function testSnmpQuery($query)
         $request = $this->getMockBuilder(\Glpi\Inventory\Request::class)
             ->onlyMethods(['inventory', 'prolog'])
             ->getMock();
-        $request->method('inventory')->willReturn(null);
-        $request->method('prolog')->willReturn(null);
+        $request->method('inventory')->willReturnCallback(function () {
+            return;
+        });
+        $request->method('prolog')->willReturnCallback(function () {
+            return;
+        });
 
         $request->handleContentType('Application/xml');
         $request->handleRequest($data);
diff --git a/src/Glpi/Agent/Communication/AbstractRequest.php b/src/Glpi/Agent/Communication/AbstractRequest.php
index a61123a03dc..bb9f0678115 100644
--- a/src/Glpi/Agent/Communication/AbstractRequest.php
+++ b/src/Glpi/Agent/Communication/AbstractRequest.php
@@ -94,24 +94,24 @@ abstract class AbstractRequest
     const COMPRESS_BR   = 3;
     const COMPRESS_DEFLATE = 4;
 
-    /** @var integer */
-    protected $mode;
+    /** @var ?integer */
+    protected ?int $mode = null;
     /** @var string */
-    private $deviceid;
-    /** @var DOMDocument */
-    private $response;
-    /** @var integer */
-    private $compression;
+    private string $deviceid;
+    /** @var DOMDocument|array|null */
+    private DOMDocument|array|null $response = null;
+    /** @var ?integer */
+    private ?int $compression = null;
     /** @var boolean */
-    private $error = false;
+    private bool $error = false;
     /** @var boolean */
-    protected $test_rules = false;
-    /** @var \Glpi\Agent\Communication\Headers\Common */
-    protected $headers;
+    protected bool $test_rules = false;
+    /** @var Common */
+    protected Common $headers;
     /** @var int */
-    private $http_response_code = 200;
+    private int $http_response_code = 200;
     /** @var string */
-    protected $query;
+    protected string $query;
 
     public function __construct()
     {
@@ -130,7 +130,7 @@ abstract protected function initHeaders(): Common;
      *
      * @throw RuntimeException
      */
-    protected function setMode($mode)
+    protected function setMode(int $mode): void
     {
         $this->mode = $mode;
         switch ($mode) {
@@ -152,9 +152,11 @@ protected function setMode($mode)
     /**
      * Guess import mode
      *
+     * @param mixed $contents
+     *
      * @return void
      */
-    private function guessMode($contents): void
+    private function guessMode(mixed $contents): void
     {
         // In the case handleContentType() didn't set mode, just check $contents first char
         if ($contents[0] === '{') {
@@ -168,7 +170,8 @@ private function guessMode($contents): void
     /**
      * Display module name
      *
-     * @param string $internalModule
+     * @param ?string $internalModule
+     *
      * @return string readable method name
      */
     public static function getModuleName(?string $internalModule): string
@@ -191,9 +194,9 @@ public static function getModuleName(?string $internalModule): string
     /**
      * Handle request headers
      *
-     * @param $data
+     * @return void
      */
-    public function handleHeaders()
+    public function handleHeaders(): void
     {
         $req_headers = getallheaders();
         $this->headers->setHeaders($req_headers);
@@ -206,7 +209,7 @@ public function handleHeaders()
      *
      * @return boolean
      */
-    public function handleRequest($data): bool
+    public function handleRequest(mixed $data): bool
     {
         $auth_required = \Config::getConfigurationValue('inventory', 'auth_required');
         if ($auth_required === Conf::CLIENT_CREDENTIALS) {
@@ -256,7 +259,7 @@ public function handleRequest($data): bool
             }
         }
 
-        // Some network inventories may request may contains lots of information.
+        // Some network inventories may request may contain lots of information.
         // e.g. a Huawei S5720-52X-LI-AC inventory file may weigh 20MB,
         // and GLPI will consume about 500MB of memory to handle it,
         // and may take up to 2 minutes on server that has low performances.
@@ -302,25 +305,22 @@ public function handleRequest($data): bool
         }
 
        //load and check data
-        switch ($this->mode) {
-            case self::XML_MODE:
-                return $this->handleXMLRequest($data);
-            case self::JSON_MODE:
-                return $this->handleJSONRequest($data);
-        }
-
-        return false;
+        return match ($this->mode) {
+            self::XML_MODE => $this->handleXMLRequest($data),
+            self::JSON_MODE => $this->handleJSONRequest($data),
+            default => false,
+        };
     }
 
     /**
      * Handle Query
      *
      * @param string $action  Action (one of self::*_ACTION)
-     * @param mixed  $content Contents, optional
+     * @param ?mixed $content Contents, optional
      *
      * @return boolean
      */
-    abstract protected function handleAction($action, $content = null): bool;
+    abstract protected function handleAction(string $action, mixed $content = null): bool;
 
     /**
      * Handle Task
@@ -329,7 +329,7 @@ abstract protected function handleAction($action, $content = null): bool;
      *
      * @return array
      */
-    abstract protected function handleTask($task): array;
+    abstract protected function handleTask(string $task): array;
 
     /**
      * Handle XML request
@@ -338,7 +338,7 @@ abstract protected function handleTask($task): array;
      *
      * @return boolean
      */
-    public function handleXMLRequest($data): bool
+    public function handleXMLRequest(string $data): bool
     {
         libxml_use_internal_errors(true);
 
@@ -377,7 +377,7 @@ public function handleXMLRequest($data): bool
      *
      * @return boolean
      */
-    public function handleJSONRequest($data): bool
+    public function handleJSONRequest(string $data): bool
     {
         if (!\Toolbox::isJSON($data)) {
             $this->addError('JSON not well formed!', 400);
@@ -402,7 +402,7 @@ public function handleJSONRequest($data): bool
      *
      * @return null|integer One of self::*_MODE
      */
-    public function getMode()
+    public function getMode(): ?int
     {
         return $this->mode;
     }
@@ -410,12 +410,12 @@ public function getMode()
     /**
      * Adds an error
      *
-     * @param string  $message Error message
+     * @param ?string $message Error message
      * @param integer $code    HTTP response code
      *
      * @return void
      */
-    public function addError($message, $code = 500)
+    public function addError(?string $message, int $code = 500): void
     {
         if ($code >= 400) {
             $this->error = true;
@@ -448,7 +448,7 @@ public function addError($message, $code = 500)
      *
      * @return void
      */
-    public function addToResponse(array $entries)
+    public function addToResponse(array $entries): void
     {
         if ($this->mode === self::XML_MODE) {
             $root = $this->response->documentElement;
@@ -472,12 +472,12 @@ public function addToResponse(array $entries)
      * Add node to response for XML_MODE
      *
      * @param DOMElement        $parent  Parent element
-     * @param string            $name    Element name to create
-     * @param string|array|null $content Element contents, if any
+     * @param ?mixed            $name    Element name to create
+     * @param array|string|null $content Element contents, if any
      *
      * @return void
      */
-    private function addNode(DOMElement $parent, $name, $content)
+    private function addNode(DOMElement $parent, mixed $name, array|string|null $content): void
     {
         if (is_array($content) && !isset($content['content']) && !isset($content['attributes'])) {
             $node = is_string($name)
@@ -544,14 +544,11 @@ public function getContentType(): string
             }
         }
 
-        switch ($this->mode) {
-            case self::XML_MODE:
-                return 'application/xml';
-            case self::JSON_MODE:
-                return 'application/json';
-            default:
-                throw new \RuntimeException("Unknown mode " . $this->mode);
-        }
+        return match ($this->mode) {
+            self::XML_MODE => 'application/xml',
+            self::JSON_MODE => 'application/json',
+            default => throw new \RuntimeException("Unknown mode " . $this->mode),
+        };
     }
 
     /**
@@ -568,16 +565,11 @@ public function getResponse(): string
                 throw new \RuntimeException("Mode has not been set");
             }
 
-            switch ($this->mode) {
-                case self::XML_MODE:
-                    $data = trim($this->response->saveXML());
-                    break;
-                case self::JSON_MODE:
-                    $data = json_encode($this->response);
-                    break;
-                default:
-                    throw new \UnexpectedValueException("Unknown mode " . $this->mode);
-            }
+            $data = match ($this->mode) {
+                self::XML_MODE => trim($this->response->saveXML()),
+                self::JSON_MODE => json_encode($this->response),
+                default => throw new \UnexpectedValueException("Unknown mode " . $this->mode),
+            };
 
             if ($this->compression === null) {
                 throw new \RuntimeException("Compression has not been set");
@@ -620,7 +612,7 @@ public function getResponse(): string
      *
      * @return void
      */
-    public function handleContentType($type)
+    public function handleContentType(string $type): void
     {
         switch (strtolower($type)) {
             case 'application/x-zlib':
@@ -663,7 +655,7 @@ public function handleContentType($type)
      *
      * @return boolean
      */
-    public function inError()
+    public function inError(): bool
     {
         return $this->error;
     }
@@ -698,7 +690,7 @@ public function acceptedEncodings(): array
      *
      * @return void
      */
-    private function prepareHeaders()
+    private function prepareHeaders(): void
     {
         $headers = [
             'Content-Type' => $this->getContentType(),
@@ -713,7 +705,7 @@ private function prepareHeaders()
      *
      * @return array
      */
-    public function getHeaders($legacy = true): array
+    public function getHeaders(bool $legacy = true): array
     {
         return $this->headers->getHeaders($legacy);
     }
diff --git a/src/Glpi/Agent/Communication/Headers/Common.php b/src/Glpi/Agent/Communication/Headers/Common.php
index aef2dc9cf0e..e3a4b53391f 100644
--- a/src/Glpi/Agent/Communication/Headers/Common.php
+++ b/src/Glpi/Agent/Communication/Headers/Common.php
@@ -46,7 +46,7 @@ class Common
      *
      * @var string
      */
-    protected $content_type;
+    protected string $content_type;
 
     /**
      * "Accept" HTTP header
@@ -55,7 +55,7 @@ class Common
      *
      * @var string
      */
-    protected $accept;
+    protected string $accept;
 
     /**
      * "Cache-Control" HTTP header
@@ -63,7 +63,7 @@ class Common
      *
      * @var string
      */
-    protected $cache_control = 'no-cache,no-store';
+    protected string $cache_control = 'no-cache,no-store';
 
     /**
      * "Connection" HTTP header
@@ -71,7 +71,7 @@ class Common
      *
      * @var string
      */
-    protected $connection = 'close';
+    protected string $connection = 'close';
 
     /**
      * "Pragma" HTTP header
@@ -81,7 +81,7 @@ class Common
      *
      * @var string
      */
-    protected $pragma = 'no-cache';
+    protected string $pragma = 'no-cache';
 
    //GLPI agent headers
     /**
@@ -92,7 +92,7 @@ class Common
      *
      * @var string
      */
-    protected $glpi_agent_id;
+    protected string $glpi_agent_id;
 
     /**
      * "GLPI-Request-ID" HTTP header
@@ -101,7 +101,7 @@ class Common
      *
      * @var string
      */
-    protected $glpi_request_id;
+    protected string $glpi_request_id;
 
     /**
      * "GLPI-CryptoKey-ID" HTTP header
@@ -110,7 +110,7 @@ class Common
      *
      * @var string
      */
-    protected $glpi_cryptokey_id;
+    protected string $glpi_cryptokey_id;
 
     /**
      * "GLPI-Proxy-ID" HTTP header
@@ -119,19 +119,19 @@ class Common
      *
      * @var string
      */
-    protected $glpi_proxy_id;
+    protected string $glpi_proxy_id;
 
     /**
      * Authorization header
-     * @var string
+     * @var ?string
      */
-    protected $authorization;
+    protected ?string $authorization = null;
 
     /**
      * Define HTTP Authorization Header Authorization type
      * @var string
      */
-    protected $www_authenticate;
+    protected string $www_authenticate;
 
     public function getRequireds(): array
     {
@@ -158,7 +158,7 @@ public function getHeadersNames(): array
      *
      * @return array
      */
-    public function getHeaders($legacy = true): array
+    public function getHeaders(bool $legacy = true): array
     {
        //parse class attributes and normalize key name
         $reflect = new ReflectionClass($this);
@@ -188,8 +188,10 @@ public function getHeaders($legacy = true): array
      * Get header value
      *
      * @param string $name Header name
+     *
+     * @return mixed
      */
-    public function getHeader($name)
+    public function getHeader(string $name): mixed
     {
         $propname = strtolower(str_replace('-', '_', $name));
 
@@ -203,7 +205,7 @@ public function getHeader($name)
      *
      * @return string
      */
-    final public function getHeaderName($prop): string
+    final public function getHeaderName(string $prop): string
     {
         $name = $prop;
 
@@ -231,11 +233,11 @@ final public function getHeaderName($prop): string
     /**
      * Set multiple HTTP header values at once
      *
-     * @param $headers Array of HTTP header name as key and value
+     * @param array $headers Array of HTTP header name as key and value
      *
      * @return $this
      */
-    public function setHeaders($headers): self
+    public function setHeaders(array $headers): self
     {
         foreach ($headers as $header => $value) {
             $this->setHeader($header, $value);
@@ -246,12 +248,12 @@ public function setHeaders($headers): self
     /**
      * Set HTTP header value
      *
-     * @param $name HTTP header name
-     * @param $value Value to set
+     * @param string $name  HTTP header name
+     * @param mixed  $value Value to set
      *
      * @return $this
      */
-    public function setHeader($name, $value): self
+    public function setHeader(string $name, mixed $value): self
     {
         $propname = strtolower(str_replace('-', '_', $name));
         if (property_exists($this, $propname)) {
@@ -267,7 +269,7 @@ public function setHeader($name, $value): self
      *
      * @return bool
      */
-    public function hasHeader($name): bool
+    public function hasHeader(string $name): bool
     {
         $propname = strtolower(str_replace('-', '_', $name));
         return property_exists($this, $propname) && !empty($this->$propname);
diff --git a/src/Glpi/Inventory/Request.php b/src/Glpi/Inventory/Request.php
index ece8368b292..c8c216f12fd 100644
--- a/src/Glpi/Inventory/Request.php
+++ b/src/Glpi/Inventory/Request.php
@@ -50,7 +50,7 @@
 class Request extends AbstractRequest
 {
     /** @var Inventory */
-    private $inventory;
+    private Inventory $inventory;
 
     /** @var bool */
     private bool $is_discovery = false;
@@ -67,15 +67,15 @@ protected function initHeaders(): Common
     /**
      * Handle Query
      *
-     * @param string $query   Query mode (one of self::*_QUERY or self::*_ACTION)
-     * @param mixed  $content Contents, optional
+     * @param string $action   Query mode (one of self::*_QUERY or self::*_ACTION)
+     * @param mixed|null $content Contents, optional
      *
      * @return boolean
      */
-    protected function handleAction($query, $content = null): bool
+    protected function handleAction(string $action, mixed $content = null): bool
     {
-        $this->query = $query;
-        switch ($query) {
+        $this->query = $action;
+        switch ($action) {
             case self::GET_PARAMS:
                 $this->getParams($content);
                 break;
@@ -104,7 +104,7 @@ protected function handleAction($query, $content = null): bool
             case self::DEPLOY_ACTION:
             case self::WOL_ACTION:
             default:
-                $this->addError("Query '$query' is not supported.", 501);
+                $this->addError("Query '$action' is not supported.", 501);
                 return false;
         }
         return true;
@@ -117,7 +117,7 @@ protected function handleAction($query, $content = null): bool
      *
      * @return array
      */
-    protected function handleTask($task): array
+    protected function handleTask(string $task): array
     {
         $params = [
             'options' => [
@@ -156,7 +156,7 @@ protected function handleTask($task): array
      *
      * @return void
      */
-    public function getParams($data)
+    public function getParams(mixed $data): void
     {
         /** @var array $CFG_GLPI */
         global $CFG_GLPI;
@@ -190,7 +190,7 @@ public function getParams($data)
      *
      * @return void
      */
-    public function prolog($data)
+    public function prolog(mixed $data): void
     {
         /** @var array $CFG_GLPI */
         global $CFG_GLPI;
@@ -231,7 +231,7 @@ public function prolog($data)
      *
      * @return void
      */
-    public function networkDiscovery($data)
+    public function networkDiscovery(mixed $data): void
     {
         $this->network_inventory_mode = Hooks::NETWORK_DISCOVERY;
         $this->is_discovery = true;
@@ -246,7 +246,7 @@ public function networkDiscovery($data)
      *
      * @return void
      */
-    public function networkInventory($data)
+    public function networkInventory(mixed $data): void
     {
         $this->network_inventory_mode = Hooks::NETWORK_INVENTORY;
         $this->network($data);
@@ -259,7 +259,7 @@ public function networkInventory($data)
      *
      * @return void
      */
-    public function network($data)
+    public function network(mixed $data): void
     {
         $this->inventory = new Inventory();
         $this->inventory
@@ -303,7 +303,7 @@ public function network($data)
      *
      * @return void
      */
-    public function contact($data)
+    public function contact(mixed $data): void
     {
         /** @var array $CFG_GLPI */
         global $CFG_GLPI;
@@ -321,7 +321,7 @@ public function contact($data)
         if ($raw_data !== null && property_exists($raw_data, 'enabled-tasks')) {
             foreach ($raw_data->{'enabled-tasks'} as $task) {
                 $handle = $this->handleTask($task);
-                if (is_array($handle) && count($handle)) {
+                if (count($handle)) {
                     // Insert related task information under tasks list property
                     $response['tasks'][$task] = $handle;
                 } else {
@@ -344,7 +344,7 @@ public function contact($data)
      *
      * @return void
      */
-    public function inventory($data)
+    public function inventory(mixed $data): void
     {
         /** @var array $CFG_GLPI */
         global $CFG_GLPI;
diff --git a/tests/web/Glpi/Inventory/Request.php b/tests/web/Glpi/Inventory/Request.php
index f8eb4dbbb67..b136f6541d9 100644
--- a/tests/web/Glpi/Inventory/Request.php
+++ b/tests/web/Glpi/Inventory/Request.php
@@ -41,8 +41,8 @@
 
 class Request extends \DBTestCase
 {
-    private $http_client;
-    private $base_uri;
+    private GuzzleHttp\Client $http_client;
+    private string $base_uri;
 
     public function beforeTestMethod($method)
     {