Add PSR-3 compliant exception context when logging exceptions (#300)

* Add PSR-3 exception context to caught error logs

* Apply review feedback

src/Capability/Discovery/Discoverer.php

@@ -117,7 +117,6 @@ final class Discoverer implements DiscovererInterface
         } catch (\Throwable $e) {
             $this->logger->error('Error during file finding process for MCP discovery'.json_encode($e->getTrace(), \JSON_PRETTY_PRINT), [
                 'exception' => $e,
-                'trace' => $e->getTraceAsString(),
             ]);
         }
 
@@ -199,7 +198,6 @@ final class Discoverer implements DiscovererInterface
                 'file' => $file->getPathname(),
                 'class' => $className,
                 'exception' => $e,
-                'trace' => $e->getTraceAsString(),
             ]);
         }
     }
@@ -300,9 +298,15 @@ final class Discoverer implements DiscovererInterface
                     break;
             }
         } catch (ExceptionInterface $e) {
-            $this->logger->error("Failed to process MCP attribute on {$className}::{$methodName}", ['attribute' => $attributeClassName, 'exception' => $e, 'trace' => $e->getPrevious() ? $e->getPrevious()->getTraceAsString() : $e->getTraceAsString()]);
+            $this->logger->error("Failed to process MCP attribute on {$className}::{$methodName}", [
+                'attribute' => $attributeClassName,
+                'exception' => $e,
+            ]);
         } catch (\Throwable $e) {
-            $this->logger->error("Unexpected error processing attribute on {$className}::{$methodName}", ['attribute' => $attributeClassName, 'exception' => $e, 'trace' => $e->getTraceAsString()]);
+            $this->logger->error("Unexpected error processing attribute on {$className}::{$methodName}", [
+                'attribute' => $attributeClassName,
+                'exception' => $e,
+            ]);
         }
     }
 

src/Capability/Discovery/DocBlockParser.php

@@ -47,8 +47,7 @@ class DocBlockParser
         } catch (\Throwable $e) {
             // Log error or handle gracefully if invalid DocBlock syntax is encountered
             $this->logger->warning('Failed to parse DocBlock', [
-                'error' => $e->getMessage(),
+                'exception' => $e,
-                'exception_trace' => $e->getTraceAsString(),
             ]);
 
             return null;

src/Capability/Discovery/SchemaValidator.php

@@ -87,8 +87,7 @@ class SchemaValidator
             $result = $validator->validate($dataToValidate, $schemaObject);
         } catch (\Throwable $e) {
             $this->logger->error('MCP SDK: JSON Schema validation failed internally.', [
-                'exception_message' => $e->getMessage(),
+                'exception' => $e,
-                'exception_trace' => $e->getTraceAsString(),
                 'data' => json_encode($dataToValidate),
                 'schema' => json_encode($schemaObject),
             ]);

src/Client/Handler/Request/SamplingRequestHandler.php

@@ -55,7 +55,7 @@ class SamplingRequestHandler implements RequestHandlerInterface
 
             return new Response($request->getId(), $result);
         } catch (SamplingException $e) {
-            $this->logger->error('Sampling failed: '.$e->getMessage());
+            $this->logger->error('Sampling failed: '.$e->getMessage(), ['exception' => $e]);
 
             return Error::forInternalError($e->getMessage(), $request->getId());
         } catch (\Throwable $e) {

src/Client/Transport/HttpTransport.php

@@ -170,7 +170,7 @@ class HttpTransport extends BaseTransport
                 $this->httpClient->sendRequest($request);
                 $this->logger->info('Session closed', ['session_id' => $this->sessionId]);
             } catch (\Throwable $e) {
-                $this->logger->warning('Failed to close session', ['error' => $e->getMessage()]);
+                $this->logger->warning('Failed to close session', ['exception' => $e]);
             }
         }
 

src/Server/Handler/Request/CallToolHandler.php

@@ -65,7 +65,7 @@ final class CallToolHandler implements RequestHandlerInterface
         try {
             $reference = $this->registry->getTool($toolName);
         } catch (ToolNotFoundException $e) {
-            $this->logger->error('Tool not found', ['name' => $toolName]);
+            $this->logger->error('Tool not found', ['name' => $toolName, 'exception' => $e]);
 
             return new Error($request->getId(), Error::METHOD_NOT_FOUND, $e->getMessage());
         }
@@ -112,6 +112,7 @@ final class CallToolHandler implements RequestHandlerInterface
             $this->logger->error(\sprintf('Error while executing tool "%s": "%s".', $toolName, $e->getMessage()), [
                 'tool' => $toolName,
                 'arguments' => $arguments,
+                'exception' => $e,
             ]);
 
             $errorContent = [new TextContent($e->getMessage())];

src/Server/Handler/Request/GetPromptHandler.php

@@ -65,15 +65,15 @@ final class GetPromptHandler implements RequestHandlerInterface
 
             return new Response($request->getId(), new GetPromptResult($formatted));
         } catch (PromptGetException $e) {
-            $this->logger->error(\sprintf('Error while handling prompt "%s": "%s".', $promptName, $e->getMessage()));
+            $this->logger->error(\sprintf('Error while handling prompt "%s": "%s".', $promptName, $e->getMessage()), ['exception' => $e]);
 
             return Error::forInternalError($e->getMessage(), $request->getId());
         } catch (PromptNotFoundException $e) {
-            $this->logger->error('Prompt not found', ['prompt_name' => $promptName]);
+            $this->logger->error('Prompt not found', ['prompt_name' => $promptName, 'exception' => $e]);
 
             return Error::forResourceNotFound($e->getMessage(), $request->getId());
         } catch (\Throwable $e) {
-            $this->logger->error(\sprintf('Unexpected error while handling prompt "%s": "%s".', $promptName, $e->getMessage()));
+            $this->logger->error(\sprintf('Unexpected error while handling prompt "%s": "%s".', $promptName, $e->getMessage()), ['exception' => $e]);
 
             return Error::forInternalError('Error while handling prompt', $request->getId());
         }

src/Server/Handler/Request/ReadResourceHandler.php

@@ -77,15 +77,15 @@ final class ReadResourceHandler implements RequestHandlerInterface
 
             return new Response($request->getId(), new ReadResourceResult($formatted));
         } catch (ResourceReadException $e) {
-            $this->logger->error(\sprintf('Error while reading resource "%s": "%s".', $uri, $e->getMessage()));
+            $this->logger->error(\sprintf('Error while reading resource "%s": "%s".', $uri, $e->getMessage()), ['exception' => $e]);
 
             return Error::forInternalError($e->getMessage(), $request->getId());
         } catch (ResourceNotFoundException $e) {
-            $this->logger->error('Resource not found', ['uri' => $uri]);
+            $this->logger->error('Resource not found', ['uri' => $uri, 'exception' => $e]);
 
             return Error::forResourceNotFound($e->getMessage(), $request->getId());
         } catch (\Throwable $e) {
-            $this->logger->error(\sprintf('Unexpected error while reading resource "%s": "%s".', $uri, $e->getMessage()));
+            $this->logger->error(\sprintf('Unexpected error while reading resource "%s": "%s".', $uri, $e->getMessage()), ['exception' => $e]);
 
             return Error::forInternalError('Error while reading resource', $request->getId());
         }

src/Server/Handler/Request/ResourceSubscribeHandler.php

@@ -55,7 +55,7 @@ final class ResourceSubscribeHandler implements RequestHandlerInterface
         try {
             $this->registry->getResource($uri);
         } catch (ResourceNotFoundException $e) {
-            $this->logger->error('Resource not found', ['uri' => $uri]);
+            $this->logger->error('Resource not found', ['uri' => $uri, 'exception' => $e]);
 
             return Error::forResourceNotFound($e->getMessage(), $request->getId());
         }

src/Server/Handler/Request/ResourceUnsubscribeHandler.php

@@ -55,7 +55,7 @@ final class ResourceUnsubscribeHandler implements RequestHandlerInterface
         try {
             $this->registry->getResource($uri);
         } catch (ResourceNotFoundException $e) {
-            $this->logger->error('Resource not found', ['uri' => $uri]);
+            $this->logger->error('Resource not found', ['uri' => $uri, 'exception' => $e]);
 
             return Error::forResourceNotFound($e->getMessage(), $request->getId());
         }

tests/Conformance/client.php

@@ -96,7 +96,7 @@ try {
     $logger->info('Disconnected');
     exit(0);
 } catch (Throwable $e) {
-    $logger->error(sprintf('Error: %s', $e->getMessage()));
+    $logger->error(sprintf('Error: %s', $e->getMessage()), ['exception' => $e]);
     fwrite(\STDERR, sprintf("Error: %s\n%s\n", $e->getMessage(), $e->getTraceAsString()));
 
     try {

tests/Unit/Server/Handler/Request/CallToolHandlerTest.php

@@ -166,16 +166,18 @@ class CallToolHandlerTest extends TestCase
     public function testHandleToolNotFoundExceptionReturnsError(): void
     {
         $request = $this->createCallToolRequest('nonexistent_tool', ['param' => 'value']);
+        $exception = new ToolNotFoundException('nonexistent_tool');
 
         $this->registry
             ->expects($this->once())
             ->method('getTool')
             ->with('nonexistent_tool')
-            ->willThrowException(new ToolNotFoundException('nonexistent_tool'));
+            ->willThrowException($exception);
 
         $this->logger
             ->expects($this->once())
-            ->method('error');
+            ->method('error')
+            ->with('Tool not found', ['name' => 'nonexistent_tool', 'exception' => $exception]);
 
         $response = $this->handler->handle($request, $this->session);
 
@@ -206,7 +208,15 @@ class CallToolHandlerTest extends TestCase
 
         $this->logger
             ->expects($this->once())
-            ->method('error');
+            ->method('error')
+            ->with(
+                'Error while executing tool "failing_tool": "Tool execution failed".',
+                [
+                    'tool' => 'failing_tool',
+                    'arguments' => ['param' => 'value', '_session' => $this->session, '_request' => $request],
+                    'exception' => $exception,
+                ],
+            );
 
         $response = $this->handler->handle($request, $this->session);
 
@@ -288,6 +298,7 @@ class CallToolHandlerTest extends TestCase
                 [
                     'tool' => 'test_tool',
                     'arguments' => ['key1' => 'value1', 'key2' => 42, '_session' => $this->session, '_request' => $request],
+                    'exception' => $exception,
                 ],
             );
 

tests/Unit/Server/Handler/Request/GetPromptHandlerTest.php

@@ -27,6 +27,7 @@ use Mcp\Server\Handler\Request\GetPromptHandler;
 use Mcp\Server\Session\SessionInterface;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
+use Psr\Log\LoggerInterface;
 
 class GetPromptHandlerTest extends TestCase
 {
@@ -34,14 +35,16 @@ class GetPromptHandlerTest extends TestCase
     private RegistryInterface&MockObject $referenceProvider;
     private ReferenceHandlerInterface&MockObject $referenceHandler;
     private SessionInterface&MockObject $session;
+    private LoggerInterface&MockObject $logger;
 
     protected function setUp(): void
     {
         $this->referenceProvider = $this->createMock(RegistryInterface::class);
         $this->referenceHandler = $this->createMock(ReferenceHandlerInterface::class);
         $this->session = $this->createMock(SessionInterface::class);
+        $this->logger = $this->createMock(LoggerInterface::class);
 
-        $this->handler = new GetPromptHandler($this->referenceProvider, $this->referenceHandler);
+        $this->handler = new GetPromptHandler($this->referenceProvider, $this->referenceHandler, $this->logger);
     }
 
     public function testSupportsGetPromptRequest(): void
@@ -239,6 +242,11 @@ class GetPromptHandlerTest extends TestCase
             ->with('nonexistent_prompt')
             ->willThrowException($exception);
 
+        $this->logger
+            ->expects($this->once())
+            ->method('error')
+            ->with('Prompt not found', ['prompt_name' => 'nonexistent_prompt', 'exception' => $exception]);
+
         $response = $this->handler->handle($request, $this->session);
 
         $this->assertInstanceOf(Error::class, $response);
@@ -258,6 +266,11 @@ class GetPromptHandlerTest extends TestCase
             ->with('failing_prompt')
             ->willThrowException($exception);
 
+        $this->logger
+            ->expects($this->once())
+            ->method('error')
+            ->with('Error while handling prompt "failing_prompt": "Failed to get prompt".', ['exception' => $exception]);
+
         $response = $this->handler->handle($request, $this->session);
 
         $this->assertInstanceOf(Error::class, $response);

tests/Unit/Server/Handler/Request/ReadResourceHandlerTest.php

@@ -27,6 +27,7 @@ use Mcp\Server\Handler\Request\ReadResourceHandler;
 use Mcp\Server\Session\SessionInterface;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
+use Psr\Log\LoggerInterface;
 
 class ReadResourceHandlerTest extends TestCase
 {
@@ -34,14 +35,16 @@ class ReadResourceHandlerTest extends TestCase
     private RegistryInterface&MockObject $registry;
     private ReferenceHandlerInterface&MockObject $referenceHandler;
     private SessionInterface&MockObject $session;
+    private LoggerInterface&MockObject $logger;
 
     protected function setUp(): void
     {
         $this->registry = $this->createMock(RegistryInterface::class);
         $this->referenceHandler = $this->createMock(ReferenceHandlerInterface::class);
         $this->session = $this->createMock(SessionInterface::class);
+        $this->logger = $this->createMock(LoggerInterface::class);
 
-        $this->handler = new ReadResourceHandler($this->registry, $this->referenceHandler);
+        $this->handler = new ReadResourceHandler($this->registry, $this->referenceHandler, $this->logger);
     }
 
     public function testSupportsReadResourceRequest(): void
@@ -186,6 +189,11 @@ class ReadResourceHandlerTest extends TestCase
             ->with($uri)
             ->willThrowException($exception);
 
+        $this->logger
+            ->expects($this->once())
+            ->method('error')
+            ->with('Resource not found', ['uri' => $uri, 'exception' => $exception]);
+
         $response = $this->handler->handle($request, $this->session);
 
         $this->assertInstanceOf(Error::class, $response);
@@ -206,6 +214,11 @@ class ReadResourceHandlerTest extends TestCase
             ->with($uri)
             ->willThrowException($exception);
 
+        $this->logger
+            ->expects($this->once())
+            ->method('error')
+            ->with('Error while reading resource "file://corrupted/file.txt": "Failed to read resource: corrupted data".', ['exception' => $exception]);
+
         $response = $this->handler->handle($request, $this->session);
 
         $this->assertInstanceOf(Error::class, $response);
@@ -226,6 +239,11 @@ class ReadResourceHandlerTest extends TestCase
             ->with($uri)
             ->willThrowException($exception);
 
+        $this->logger
+            ->expects($this->once())
+            ->method('error')
+            ->with('Unexpected error while reading resource "file://problematic/file.txt": "Internal database connection failed".', ['exception' => $exception]);
+
         $response = $this->handler->handle($request, $this->session);
 
         $this->assertInstanceOf(Error::class, $response);

tests/Unit/Server/Handler/Request/ResourceSubscribeTest.php

@@ -26,6 +26,7 @@ use Mcp\Server\Session\SessionInterface;
 use PHPUnit\Framework\Attributes\TestDox;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
+use Psr\Log\LoggerInterface;
 
 class ResourceSubscribeTest extends TestCase
 {
@@ -33,13 +34,15 @@ class ResourceSubscribeTest extends TestCase
     private RegistryInterface&MockObject $registry;
     private SessionInterface&MockObject $session;
     private SubscriptionManagerInterface&MockObject $subscriptionManager;
+    private LoggerInterface&MockObject $logger;
 
     protected function setUp(): void
     {
         $this->registry = $this->createMock(RegistryInterface::class);
         $this->subscriptionManager = $this->createMock(SubscriptionManagerInterface::class);
         $this->session = $this->createMock(SessionInterface::class);
-        $this->handler = new ResourceSubscribeHandler($this->registry, $this->subscriptionManager);
+        $this->logger = $this->createMock(LoggerInterface::class);
+        $this->handler = new ResourceSubscribeHandler($this->registry, $this->subscriptionManager, $this->logger);
     }
 
     #[TestDox('Client can successfully subscribe to a resource')]
@@ -121,6 +124,11 @@ class ResourceSubscribeTest extends TestCase
             ->with($uri)
             ->willThrowException($exception);
 
+        $this->logger
+            ->expects($this->once())
+            ->method('error')
+            ->with('Resource not found', ['uri' => $uri, 'exception' => $exception]);
+
         $response = $this->handler->handle($request, $this->session);
 
         $this->assertInstanceOf(Error::class, $response);

tests/Unit/Server/Handler/Request/ResourceUnsubscribeTest.php

@@ -26,6 +26,7 @@ use Mcp\Server\Session\SessionInterface;
 use PHPUnit\Framework\Attributes\TestDox;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
+use Psr\Log\LoggerInterface;
 
 class ResourceUnsubscribeTest extends TestCase
 {
@@ -33,14 +34,16 @@ class ResourceUnsubscribeTest extends TestCase
     private RegistryInterface&MockObject $registry;
     private SessionInterface&MockObject $session;
     private SubscriptionManagerInterface&MockObject $subscriptionManager;
+    private LoggerInterface&MockObject $logger;
 
     protected function setUp(): void
     {
         $this->registry = $this->createMock(RegistryInterface::class);
         $this->subscriptionManager = $this->createMock(SubscriptionManagerInterface::class);
         $this->session = $this->createMock(SessionInterface::class);
+        $this->logger = $this->createMock(LoggerInterface::class);
 
-        $this->handler = new ResourceUnsubscribeHandler($this->registry, $this->subscriptionManager);
+        $this->handler = new ResourceUnsubscribeHandler($this->registry, $this->subscriptionManager, $this->logger);
     }
 
     #[TestDox('Client can unsubscribe from a resource')]
@@ -119,6 +122,11 @@ class ResourceUnsubscribeTest extends TestCase
             ->with($uri)
             ->willThrowException($exception);
 
+        $this->logger
+            ->expects($this->once())
+            ->method('error')
+            ->with('Resource not found', ['uri' => $uri, 'exception' => $exception]);
+
         $response = $this->handler->handle($request, $this->session);
 
         $this->assertInstanceOf(Error::class, $response);