Adjust logging level for frequent / low-level events

Author: mattt

Sources/MCP/Base/Transports/HTTPClientTransport.swift

@@ -131,7 +131,7 @@ public actor HTTPClientTransport: Transport {
         if let continuation = self.initialSessionIDContinuation {
             continuation.resume()
             self.initialSessionIDContinuation = nil  // Consume the continuation
-            logger.debug("Initial session ID signal triggered for SSE task.")
+            logger.trace("Initial session ID signal triggered for SSE task.")
         }
     }
 
@@ -251,7 +251,7 @@ public actor HTTPClientTransport: Transport {
                 logger.warning("SSE responses aren't fully supported on Linux")
                 messageContinuation.yield(data)
             } else if contentType.contains("application/json") {
-                logger.debug("Received JSON response", metadata: ["size": "\(data.count)"])
+                logger.trace("Received JSON response", metadata: ["size": "\(data.count)"])
                 messageContinuation.yield(data)
             } else {
                 logger.warning("Unexpected content type: \(contentType)")
@@ -285,15 +285,15 @@ public actor HTTPClientTransport: Transport {
 
             if contentType.contains("text/event-stream") {
                 // For SSE, processing happens via the stream
-                logger.debug("Received SSE response, processing in streaming task")
+                logger.trace("Received SSE response, processing in streaming task")
                 try await self.processSSE(stream)
             } else if contentType.contains("application/json") {
                 // For JSON responses, collect and deliver the data
                 var buffer = Data()
                 for try await byte in stream {
                     buffer.append(byte)
                 }
-                logger.debug("Received JSON response", metadata: ["size": "\(buffer.count)"])
+                logger.trace("Received JSON response", metadata: ["size": "\(buffer.count)"])
                 messageContinuation.yield(buffer)
             } else {
                 logger.warning("Unexpected content type: \(contentType)")
@@ -390,7 +390,7 @@ public actor HTTPClientTransport: Transport {
 
             // Wait for the initial session ID signal, but only if sessionID isn't already set
             if self.sessionID == nil, let signalTask = self.initialSessionIDSignalTask {
-                logger.debug("SSE streaming task waiting for initial sessionID signal...")
+                logger.trace("SSE streaming task waiting for initial sessionID signal...")
 
                 // Race the signalTask against a timeout
                 let timeoutTask = Task {
@@ -429,14 +429,14 @@ public actor HTTPClientTransport: Transport {
                 timeoutTask.cancel()
 
                 if signalReceived {
-                    logger.debug("SSE streaming task proceeding after initial sessionID signal.")
+                    logger.trace("SSE streaming task proceeding after initial sessionID signal.")
                 } else {
                     logger.warning(
                         "Timeout waiting for initial sessionID signal. SSE stream will proceed (sessionID might be nil)."
                     )
                 }
             } else if self.sessionID != nil {
-                logger.debug(
+                logger.trace(
                     "Initial sessionID already available. Proceeding with SSE streaming task immediately."
                 )
             } else {
@@ -525,7 +525,7 @@ public actor HTTPClientTransport: Transport {
                     // Check if task has been cancelled
                     if Task.isCancelled { break }
 
-                    logger.debug(
+                    logger.trace(
                         "SSE event received",
                         metadata: [
                             "type": "\(event.event ?? "message")",

Sources/MCP/Base/Transports/NetworkTransport.swift

@@ -408,7 +408,7 @@ import Logging
                     })
             }
 
-            logger.debug("Heartbeat sent")
+            logger.trace("Heartbeat sent")
         }
 
         /// Handles connection failure
@@ -638,11 +638,11 @@ import Logging
 
                     // Check if this is a heartbeat message
                     if Heartbeat.isHeartbeat(newData) {
-                        logger.debug("Received heartbeat from peer")
+                        logger.trace("Received heartbeat from peer")
 
                         // Extract timestamp if available
                         if let heartbeat = Heartbeat.from(data: newData) {
-                            logger.debug("Heartbeat timestamp: \(heartbeat.timestamp)")
+                            logger.trace("Heartbeat timestamp: \(heartbeat.timestamp)")
                         }
 
                         // Reset the counter since we got valid data
@@ -783,7 +783,7 @@ import Logging
                             } else if let content = content {
                                 continuation.resume(returning: content)
                             } else if isComplete {
-                                self.logger.debug("Connection completed by peer")
+                                self.logger.trace("Connection completed by peer")
                                 continuation.resume(throwing: MCPError.connectionClosed)
                             } else {
                                 // EOF: Resume with empty data instead of throwing an error

Sources/MCP/Base/Transports/StdioTransport.swift

@@ -155,7 +155,7 @@ import struct Foundation.Data
                         pendingData = pendingData[(newlineIndex + 1)...]
 
                         if !messageData.isEmpty {
-                            logger.debug(
+                            logger.trace(
                                 "Message received", metadata: ["size": "\(messageData.count)"])
                             messageContinuation.yield(Data(messageData))
                         }

Sources/MCP/Client/Client.swift

@@ -659,7 +659,7 @@ public actor Client {
     // MARK: -
 
     private func handleResponse(_ response: Response<AnyMethod>) async {
-        await logger?.debug(
+        await logger?.trace(
             "Processing response",
             metadata: ["id": "\(response.id)"])
 
@@ -684,7 +684,7 @@ public actor Client {
     }
 
     private func handleMessage(_ message: Message<AnyNotification>) async {
-        await logger?.debug(
+        await logger?.trace(
             "Processing notification",
             metadata: ["method": "\(message.method)"])
 
@@ -728,7 +728,7 @@ public actor Client {
 
     // Add handler for batch responses
     private func handleBatchResponse(_ responses: [AnyResponse]) async {
-        await logger?.debug("Processing batch response", metadata: ["count": "\(responses.count)"])
+        await logger?.trace("Processing batch response", metadata: ["count": "\(responses.count)"])
         for response in responses {
             // Attempt to remove the pending request.
             // If successful, pendingRequest contains the request.

Sources/MCP/Server/Server.swift

@@ -380,7 +380,7 @@ public actor Server {
 
     /// Process a batch of requests and/or notifications
     private func handleBatch(_ batch: Batch) async throws {
-        await logger?.debug("Processing batch request", metadata: ["size": "\(batch.items.count)"])
+        await logger?.trace("Processing batch request", metadata: ["size": "\(batch.items.count)"])
 
         if batch.items.isEmpty {
             // Empty batch is invalid according to JSON-RPC spec
@@ -450,7 +450,7 @@ public actor Server {
             )
         }
 
-        await logger?.debug(
+        await logger?.trace(
             "Processing request",
             metadata: [
                 "method": "\(request.method)",
@@ -505,7 +505,7 @@ public actor Server {
     }
 
     private func handleMessage(_ message: Message<AnyNotification>) async throws {
-        await logger?.debug(
+        await logger?.trace(
             "Processing notification",
             metadata: ["method": "\(message.method)"])