diff --git a/CHANGELOG.md b/CHANGELOG.md
index 62fe3a96..844b74b3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,13 @@
 
  - New `\Scoutapm\Config\ConfigKey` class containing `public const`s for configuration key names (#83)
  - Added config key `log_level` which overrides Scout APM's minimum log level (#83)
+ - Added more new config keys (#88):
+   - `application_root` (defaults to `composer.json` location, or `$_SERVER['DOCUMENT_ROOT']`
+   - `scm_subdirectory` (defaults to `.git` location, or `application_root` value)
+   - `revision_sha` (defaults to version detected by `ocramius/package-versions`)
+   - `hostname` (defaults to value of `gethostname()`)
+   - `core_agent_permissions` (defaults to `0777`)
+ - Added warning when `name` or `key` configurations are not set
 
 ### Fixed
 
diff --git a/src/Agent.php b/src/Agent.php
index 3e276a33..c032becf 100644
--- a/src/Agent.php
+++ b/src/Agent.php
@@ -26,6 +26,8 @@
 use Scoutapm\Extension\ExtentionCapabilities;
 use Scoutapm\Extension\PotentiallyAvailableExtensionCapabilities;
 use Scoutapm\Logger\FilteredLogLevelDecorator;
+use function is_string;
+use function sprintf;
 
 final class Agent implements ScoutApmAgent
 {
@@ -72,11 +74,27 @@ public function __construct(Config $configuration, Connector $connector, LoggerI
             );
         }
 
+        if ($this->config->get(ConfigKey::MONITORING_ENABLED)) {
+            $this->warnIfConfigValueIsNotSet(ConfigKey::APPLICATION_NAME);
+            $this->warnIfConfigValueIsNotSet(ConfigKey::APPLICATION_KEY);
+        }
+
         $this->request = new Request();
 
         $this->ignoredEndpoints = new IgnoredEndpoints($configuration->get(ConfigKey::IGNORED_ENDPOINTS));
     }
 
+    private function warnIfConfigValueIsNotSet(string $configKey) : void
+    {
+        $configValue = $this->config->get($configKey);
+
+        if ($configValue !== null && (! is_string($configValue) || $configValue !== '')) {
+            return;
+        }
+
+        $this->logger->warning(sprintf('Config key "%s" should be set, but it was empty', $configKey));
+    }
+
     private static function createConnectorFromConfig(Config $config) : SocketConnector
     {
         return new SocketConnector($config->get(ConfigKey::CORE_AGENT_SOCKET_PATH));
@@ -120,7 +138,8 @@ public function connect() : void
                     $this->config->get(ConfigKey::CORE_AGENT_DIRECTORY) . '/' . $this->config->get(ConfigKey::CORE_AGENT_FULL_NAME),
                     $this->config->get(ConfigKey::CORE_AGENT_FULL_NAME),
                     $this->logger,
-                    $this->config->get(ConfigKey::CORE_AGENT_DOWNLOAD_URL)
+                    $this->config->get(ConfigKey::CORE_AGENT_DOWNLOAD_URL),
+                    $this->config->get(ConfigKey::CORE_AGENT_PERMISSIONS)
                 )
             );
             $manager->launch();
@@ -275,7 +294,8 @@ public function send() : bool
             }
 
             if (! $this->connector->sendCommand(new Metadata(
-                new DateTimeImmutable('now', new DateTimeZone('UTC'))
+                new DateTimeImmutable('now', new DateTimeZone('UTC')),
+                $this->config
             ))) {
                 return false;
             }
diff --git a/src/Config/ConfigKey.php b/src/Config/ConfigKey.php
index 9fa929dd..d503a71e 100644
--- a/src/Config/ConfigKey.php
+++ b/src/Config/ConfigKey.php
@@ -12,6 +12,10 @@ abstract class ConfigKey
     public const LOG_LEVEL                   = 'log_level';
     public const API_VERSION                 = 'api_version';
     public const IGNORED_ENDPOINTS           = 'ignore';
+    public const APPLICATION_ROOT            = 'application_root';
+    public const SCM_SUBDIRECTORY            = 'scm_subdirectory';
+    public const REVISION_SHA                = 'revision_sha';
+    public const HOSTNAME                    = 'hostname';
     public const CORE_AGENT_LOG_LEVEL        = 'core_agent_log_level';
     public const CORE_AGENT_LOG_FILE         = 'core_agent_log_file';
     public const CORE_AGENT_CONFIG_FILE      = 'core_agent_config_file';
@@ -23,4 +27,5 @@ abstract class ConfigKey
     public const CORE_AGENT_DOWNLOAD_ENABLED = 'core_agent_download';
     public const CORE_AGENT_VERSION          = 'core_agent_version';
     public const CORE_AGENT_TRIPLE           = 'core_agent_triple';
+    public const CORE_AGENT_PERMISSIONS      = 'core_agent_permissions';
 }
diff --git a/src/Config/Source/DefaultSource.php b/src/Config/Source/DefaultSource.php
index 39e6de5e..e98bea6d 100644
--- a/src/Config/Source/DefaultSource.php
+++ b/src/Config/Source/DefaultSource.php
@@ -16,7 +16,7 @@
 /** @internal */
 class DefaultSource
 {
-    /** @var array<string, (string|bool|array<int, string>)> */
+    /** @var array<string, (string|bool|array<int, string>|int)> */
     private $defaults;
 
     public function __construct()
@@ -37,7 +37,7 @@ public function hasKey(string $key) : bool
      *
      * Only valid if the Source has previously returned "true" to `hasKey`
      *
-     * @return string|bool|array<int, string>|null
+     * @return string|bool|array<int, string>|int|null
      */
     public function get(string $key)
     {
@@ -49,7 +49,7 @@ public function get(string $key)
      *
      * Only valid if the Source has previously returned "true" to `hasKey`
      *
-     * @return array<string, (string|bool|array<int, string>)>
+     * @return array<string, (string|bool|array<int, string>|int)>
      */
     private function getDefaultConfig() : array
     {
@@ -60,6 +60,7 @@ private function getDefaultConfig() : array
             ConfigKey::CORE_AGENT_LAUNCH_ENABLED => true,
             ConfigKey::CORE_AGENT_VERSION => 'v1.2.2',
             ConfigKey::CORE_AGENT_DOWNLOAD_URL => 'https://s3-us-west-1.amazonaws.com/scout-public-downloads/apm_core_agent/release',
+            ConfigKey::CORE_AGENT_PERMISSIONS => 0777,
             ConfigKey::MONITORING_ENABLED => false,
             ConfigKey::IGNORED_ENDPOINTS => [],
             ConfigKey::LOG_LEVEL => 'debug',
diff --git a/src/CoreAgent/Downloader.php b/src/CoreAgent/Downloader.php
index 1dda9df1..b234d2a1 100644
--- a/src/CoreAgent/Downloader.php
+++ b/src/CoreAgent/Downloader.php
@@ -54,8 +54,16 @@ class Downloader
     /** @var string */
     private $downloadUrl;
 
-    public function __construct(string $coreAgentDir, string $coreAgentFullName, LoggerInterface $logger, string $downloadUrl)
-    {
+    /** @var int */
+    private $coreAgentPermissions;
+
+    public function __construct(
+        string $coreAgentDir,
+        string $coreAgentFullName,
+        LoggerInterface $logger,
+        string $downloadUrl,
+        int $coreAgentPermissions
+    ) {
         $this->logger = $logger;
 
         $this->coreAgentDir        = $coreAgentDir;
@@ -77,9 +85,10 @@ public function __construct(string $coreAgentDir, string $coreAgentFullName, Log
          *
          * @link https://bugs.php.net/bug.php?id=58852
          */
-        $this->package_location   = $coreAgentDir . '/' . str_replace('.', '_', $coreAgentFullName) . '.tgz';
-        $this->download_lock_path = $coreAgentDir . '/download.lock';
-        $this->downloadUrl        = $downloadUrl;
+        $this->package_location     = $coreAgentDir . '/' . str_replace('.', '_', $coreAgentFullName) . '.tgz';
+        $this->download_lock_path   = $coreAgentDir . '/download.lock';
+        $this->downloadUrl          = $downloadUrl;
+        $this->coreAgentPermissions = $coreAgentPermissions;
     }
 
     public function download() : void
@@ -104,12 +113,13 @@ public function download() : void
     private function createCoreAgentDir() : void
     {
         try {
-            $permissions = 0777; // TODO: AgentContext.instance.config.core_agent_permissions()
             $recursive   = true;
             $destination = $this->coreAgentDir;
 
-            if (! is_dir($destination)) {
-                mkdir($destination, $permissions, $recursive);
+            if (! is_dir($destination)
+                && ! mkdir($destination, $this->coreAgentPermissions, $recursive)
+                && ! is_dir($destination)) {
+                throw new RuntimeException(sprintf('Directory "%s" was not created', $destination));
             }
         } catch (Throwable $e) {
             $this->logger->error('Failed to create directory: ' . $destination);
diff --git a/src/Events/Metadata.php b/src/Events/Metadata.php
index eefa21c7..f7044ba4 100644
--- a/src/Events/Metadata.php
+++ b/src/Events/Metadata.php
@@ -6,13 +6,22 @@
 
 use DateTimeImmutable;
 use PackageVersions\Versions;
+use Scoutapm\Config;
+use Scoutapm\Config\ConfigKey;
 use Scoutapm\Connector\Command;
 use Scoutapm\Helper\Timer;
 use const PHP_VERSION;
+use function array_key_exists;
 use function array_keys;
 use function array_map;
+use function dirname;
 use function explode;
+use function file_exists;
+use function getenv;
 use function gethostname;
+use function is_readable;
+use function is_string;
+use function realpath;
 
 /**
  * Also called AppServerLoad in other agents
@@ -24,11 +33,15 @@ final class Metadata implements Command
     /** @var Timer */
     private $timer;
 
-    public function __construct(DateTimeImmutable $now)
+    /** @var Config */
+    private $config;
+
+    public function __construct(DateTimeImmutable $now, Config $config)
     {
         // Construct and stop the timer to use its timestamp logic. This event
         // is a single point in time, not a range.
-        $this->timer = new Timer((float) $now->format('U.u'));
+        $this->timer  = new Timer((float) $now->format('U.u'));
+        $this->config = $config;
     }
 
     /**
@@ -44,20 +57,79 @@ private function data() : array
             'framework_version' => '',
             'environment' => '',
             'app_server' => '',
-            'hostname' => gethostname(),
+            'hostname' => $this->config->get(ConfigKey::HOSTNAME) ?? gethostname(),
             'database_engine' => '',
             'database_adapter' => '',
-            'application_name' => '',
+            'application_name' => $this->config->get(ConfigKey::APPLICATION_NAME) ?? '',
             'libraries' => $this->getLibraries(),
             'paas' => '',
-            'application_root' => '',
-            'scm_subdirectory' => '',
+            'application_root' => $this->applicationRoot(),
+            'scm_subdirectory' => $this->scmSubdirectory(),
             'git_sha' => $this->rootPackageGitSha(),
         ];
     }
 
+    /**
+     * Try to locate a file or folder in any parent directory (upwards of this library itself)
+     */
+    private function locateFileOrFolder(string $fileOrFolder) : ?string
+    {
+        // Starting 3 levels up will avoid finding scout-apm-php's own contents
+        $dir        = dirname(__DIR__, 3);
+        $rootOrHome = '/';
+
+        while (dirname($dir) !== $dir && $dir !== $rootOrHome) {
+            $fileOrFolderAttempted = $dir . '/' . $fileOrFolder;
+            if (file_exists($fileOrFolderAttempted) && is_readable($fileOrFolderAttempted)) {
+                return realpath($dir);
+            }
+            $dir = dirname($dir);
+        }
+
+        return null;
+    }
+
+    private function applicationRoot() : string
+    {
+        $applicationRootConfiguration = $this->config->get(ConfigKey::APPLICATION_ROOT);
+        if (is_string($applicationRootConfiguration) && $applicationRootConfiguration !== '') {
+            return $applicationRootConfiguration;
+        }
+
+        $composerJsonLocation = $this->locateFileOrFolder('composer.json');
+        if ($composerJsonLocation !== null) {
+            return $composerJsonLocation;
+        }
+
+        if (! array_key_exists('DOCUMENT_ROOT', $_SERVER)) {
+            return '';
+        }
+
+        return $_SERVER['DOCUMENT_ROOT'];
+    }
+
+    private function scmSubdirectory() : string
+    {
+        $scmSubdirectoryConfiguration = $this->config->get(ConfigKey::SCM_SUBDIRECTORY);
+        if (is_string($scmSubdirectoryConfiguration) && $scmSubdirectoryConfiguration !== '') {
+            return $scmSubdirectoryConfiguration;
+        }
+
+        return $this->locateFileOrFolder('.git') ?? $this->applicationRoot();
+    }
+
     private function rootPackageGitSha() : string
     {
+        $revisionShaConfiguration = $this->config->get(ConfigKey::REVISION_SHA);
+        if (is_string($revisionShaConfiguration) && $revisionShaConfiguration !== '') {
+            return $revisionShaConfiguration;
+        }
+
+        $herokuSlugCommit = getenv('HEROKU_SLUG_COMMIT');
+        if (is_string($herokuSlugCommit) && $herokuSlugCommit !== '') {
+            return $herokuSlugCommit;
+        }
+
         return explode('@', Versions::getVersion(Versions::ROOT_PACKAGE_NAME))[1];
     }
 
diff --git a/tests/Unit/AgentTest.php b/tests/Unit/AgentTest.php
index c3dfeac2..6a114c9f 100644
--- a/tests/Unit/AgentTest.php
+++ b/tests/Unit/AgentTest.php
@@ -13,11 +13,82 @@
 use Scoutapm\Config\ConfigKey;
 use Scoutapm\Events\Span\Span;
 use Scoutapm\Events\Tag\TagRequest;
+use function array_map;
+use function count;
 use function end;
+use function sprintf;
 
 /** @covers \Scoutapm\Agent */
 final class AgentTest extends TestCase
 {
+    /**
+     * @return Config[][]|string[][][]
+     *
+     * @psalm-return array<string, array{config: Config, missingKeys: array<int, string>}>
+     */
+    public function invalidConfigurationProvider() : array
+    {
+        return [
+            'withoutName' => [
+                'config' => Config::fromArray([
+                    ConfigKey::MONITORING_ENABLED => true,
+                    ConfigKey::APPLICATION_KEY => 'abc123',
+                ]),
+                'missingKeys' => [
+                    ConfigKey::APPLICATION_NAME,
+                ],
+            ],
+            'withoutKey' => [
+                'config' => Config::fromArray([
+                    ConfigKey::MONITORING_ENABLED => true,
+                    ConfigKey::APPLICATION_NAME => 'My Application',
+                ]),
+                'missingKeys' => [
+                    ConfigKey::APPLICATION_KEY,
+                ],
+            ],
+            'withoutAnything' => [
+                'config' => Config::fromArray([ConfigKey::MONITORING_ENABLED => true]),
+                'missingKeys' => [
+                    ConfigKey::APPLICATION_NAME,
+                    ConfigKey::APPLICATION_KEY,
+                ],
+            ],
+            'withoutAnythingButMonitoringIsDisabled' => [
+                'config' => Config::fromArray([]),
+                'missingKeys' => [],
+            ],
+        ];
+    }
+
+    /**
+     * @param string[]|array<int, string> $missingKeys
+     *
+     * @dataProvider invalidConfigurationProvider
+     */
+    public function testCreatingAgentWithoutRequiredConfigKeysLogsWarning(Config $config, array $missingKeys) : void
+    {
+        /** @var LoggerInterface&MockObject $logger */
+        $logger = $this->createMock(LoggerInterface::class);
+
+        $logger->expects(self::exactly(count($missingKeys)))
+            ->method('log')
+            ->withConsecutive(...array_map(
+                static function (string $missingKey) : array {
+                    return [
+                        'warning',
+                        self::stringContains(sprintf(
+                            'Config key "%s" should be set, but it was empty',
+                            $missingKey
+                        )),
+                    ];
+                },
+                $missingKeys
+            ));
+
+        Agent::fromConfig($config, $logger);
+    }
+
     public function testMinimumLogLevelCanBeSetOnConfigurationToSquelchNoisyLogMessages() : void
     {
         /** @var LoggerInterface&MockObject $logger */
@@ -26,11 +97,16 @@ public function testMinimumLogLevelCanBeSetOnConfigurationToSquelchNoisyLogMessa
         $logger->expects(self::never())
             ->method('log');
 
-        $config = new Config();
-        $config->set(ConfigKey::LOG_LEVEL, LogLevel::WARNING);
-        $config->set(ConfigKey::MONITORING_ENABLED, 'false');
+        $agent = Agent::fromConfig(
+            Config::fromArray([
+                ConfigKey::APPLICATION_NAME => 'My Application',
+                ConfigKey::APPLICATION_KEY => 'abc123',
+                ConfigKey::LOG_LEVEL => LogLevel::WARNING,
+                ConfigKey::MONITORING_ENABLED => false,
+            ]),
+            $logger
+        );
 
-        $agent = Agent::fromConfig($config, $logger);
         $agent->connect();
     }
 
@@ -47,10 +123,15 @@ public function testLogMessagesAreLoggedWhenUsingDefaultConfiguration() : void
                 []
             );
 
-        $config = new Config();
-        $config->set(ConfigKey::MONITORING_ENABLED, 'false');
+        $agent = Agent::fromConfig(
+            Config::fromArray([
+                ConfigKey::APPLICATION_NAME => 'My Application',
+                ConfigKey::APPLICATION_KEY => 'abc123',
+                ConfigKey::MONITORING_ENABLED => false,
+            ]),
+            $logger
+        );
 
-        $agent = Agent::fromConfig($config, $logger);
         $agent->connect();
     }
 
diff --git a/tests/Unit/Events/MetadataTest.php b/tests/Unit/Events/MetadataTest.php
index dfffa484..a8814b7f 100644
--- a/tests/Unit/Events/MetadataTest.php
+++ b/tests/Unit/Events/MetadataTest.php
@@ -9,6 +9,8 @@
 use Exception;
 use PackageVersions\Versions;
 use PHPUnit\Framework\TestCase;
+use Scoutapm\Config;
+use Scoutapm\Config\ConfigKey;
 use Scoutapm\Events\Metadata;
 use Scoutapm\Helper\Timer;
 use const PHP_VERSION;
@@ -18,16 +20,69 @@
 use function gethostname;
 use function json_decode;
 use function json_encode;
+use function putenv;
+use function uniqid;
 
 /** @covers \Scoutapm\Events\Metadata */
 final class MetadataTest extends TestCase
 {
     /** @throws Exception */
-    public function testMetadataSerializesToJson() : void
+    public function testMetadataFromConfigurationSerializesToJson() : void
     {
+        $config = Config::fromArray([
+            ConfigKey::APPLICATION_ROOT => '/fake/app/root',
+            ConfigKey::SCM_SUBDIRECTORY => '/fake/scm/subdirectory',
+            ConfigKey::APPLICATION_NAME => 'My amazing application',
+            ConfigKey::REVISION_SHA => 'abc123',
+            ConfigKey::HOSTNAME => 'fake-hostname.scoutapm.com',
+        ]);
+
+        $time = new DateTimeImmutable('now', new DateTimeZone('UTC'));
+
+        self::assertEquals(
+            [
+                'ApplicationEvent' => [
+                    'timestamp' => $time->format(Timer::FORMAT_FOR_CORE_AGENT),
+                    'event_value' => [
+                        'language' => 'php',
+                        'version' => PHP_VERSION,
+                        'server_time' => $time->format(Timer::FORMAT_FOR_CORE_AGENT),
+                        'framework' => 'laravel',
+                        'framework_version' => '',
+                        'environment' => '',
+                        'app_server' => '',
+                        'hostname' => 'fake-hostname.scoutapm.com',
+                        'database_engine' => '',
+                        'database_adapter' => '',
+                        'application_name' => 'My amazing application',
+                        'libraries' => array_map(
+                            static function ($package, $version) {
+                                return [$package, $version];
+                            },
+                            array_keys(Versions::VERSIONS),
+                            Versions::VERSIONS
+                        ),
+                        'paas' => '',
+                        'application_root' => '/fake/app/root',
+                        'scm_subdirectory' => '/fake/scm/subdirectory',
+                        'git_sha' => 'abc123',
+                    ],
+                    'event_type' => 'scout.metadata',
+                    'source' => 'php',
+                ],
+            ],
+            json_decode(json_encode(new Metadata($time, $config)), true)
+        );
+    }
+
+    /** @throws Exception */
+    public function testAutoDetectedMetadataSerializesToJson() : void
+    {
+        $config = Config::fromArray([]);
+
         $time = new DateTimeImmutable('now', new DateTimeZone('UTC'));
 
-        $serialized = json_encode(new Metadata($time));
+        $_SERVER['DOCUMENT_ROOT'] = '/fake/document/root';
 
         self::assertEquals(
             [
@@ -53,15 +108,33 @@ static function ($package, $version) {
                             Versions::VERSIONS
                         ),
                         'paas' => '',
-                        'application_root' => '',
-                        'scm_subdirectory' => '',
+                        'application_root' => '/fake/document/root',
+                        'scm_subdirectory' => '/fake/document/root',
                         'git_sha' => explode('@', Versions::getVersion(Versions::ROOT_PACKAGE_NAME))[1],
                     ],
                     'event_type' => 'scout.metadata',
                     'source' => 'php',
                 ],
             ],
-            json_decode($serialized, true)
+            json_decode(json_encode(new Metadata($time, $config)), true)
         );
     }
+
+    /** @throws Exception */
+    public function testHerokuSlugCommitOverridesTheGitSha() : void
+    {
+        $testHerokuSlugCommit = uniqid('testHerokuSlugCommit', true);
+
+        putenv('HEROKU_SLUG_COMMIT=' . $testHerokuSlugCommit);
+
+        self::assertSame(
+            $testHerokuSlugCommit,
+            json_decode(json_encode(new Metadata(
+                new DateTimeImmutable('now', new DateTimeZone('UTC')),
+                Config::fromArray([])
+            )), true)['ApplicationEvent']['event_value']['git_sha']
+        );
+
+        putenv('HEROKU_SLUG_COMMIT');
+    }
 }