feat(mcp): log tool call (HTTP headers) (#221)

manusa · web-flow · commit 49dcff3f2193 · 2025-07-30T15:25:07.000+02:00
Signed-off-by: Marc Nuri &lt;marc@marcnuri.com&gt;
diff --git a/pkg/mcp/common_test.go b/pkg/mcp/common_test.go
@@ -6,8 +6,6 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
-	"k8s.io/klog/v2"
-	"k8s.io/klog/v2/textlogger"
 	"net/http/httptest"
 	"os"
 	"path/filepath"
@@ -36,6 +34,8 @@ import (
 	"k8s.io/client-go/tools/clientcmd"
 	"k8s.io/client-go/tools/clientcmd/api"
 	toolswatch "k8s.io/client-go/tools/watch"
+	"k8s.io/klog/v2"
+	"k8s.io/klog/v2/textlogger"
 	"k8s.io/utils/ptr"
 	"sigs.k8s.io/controller-runtime/pkg/envtest"
 	"sigs.k8s.io/controller-runtime/tools/setup-envtest/env"
diff --git a/pkg/mcp/mcp.go b/pkg/mcp/mcp.go
@@ -1,6 +1,7 @@
 package mcp
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"k8s.io/klog/v2"
@@ -171,6 +172,12 @@ func contextFunc(ctx context.Context, r *http.Request) context.Context {
 func toolCallLoggingMiddleware(next server.ToolHandlerFunc) server.ToolHandlerFunc {
 	return func(ctx context.Context, ctr mcp.CallToolRequest) (*mcp.CallToolResult, error) {
 		klog.V(5).Infof("mcp tool call: %s(%v)", ctr.Params.Name, ctr.Params.Arguments)
+		if ctr.Header != nil {
+			buffer := bytes.NewBuffer(make([]byte, 0))
+			if err := ctr.Header.Write(buffer); err == nil {
+				klog.V(7).Infof("mcp tool call headers: %s", buffer)
+			}
+		}
 		return next(ctx, ctr)
 	}
 }
diff --git a/pkg/mcp/mcp_tools_test.go b/pkg/mcp/mcp_tools_test.go
@@ -140,4 +140,16 @@ func TestToolCallLogging(t *testing.T) {
 			}
 		})
 	})
+	testCaseWithContext(t, &mcpContext{logLevel: 7}, func(c *mcpContext) {
+		_, _ = c.callTool("configuration_view", map[string]interface{}{
+			"minified": false,
+		})
+		t.Run("Logs tool call headers", func(t *testing.T) {
+			expectedLog := "mcp tool call headers: Accept-Encoding: gzip"
+			if !strings.Contains(c.logBuffer.String(), expectedLog) {
+				t.Errorf("Expected log to contain '%s', got: %s", expectedLog, c.logBuffer.String())
+			}
+		})
+
+	})
 }
