diff --git a/register_metrics_test.go b/register_metrics_test.go
index 0a46484..e2dbe12 100644
--- a/register_metrics_test.go
+++ b/register_metrics_test.go
@@ -4,6 +4,7 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -67,4 +68,92 @@ func TestHTTPClient_MetricsIntegration(t *testing.T) {
 		defer metrics.lock.Unlock()
 		return len(metrics.pushToSeriesCalls) > 0 && len(metrics.incrCounterCalls) > 0 && len(metrics.incrCounterWithAttrsCalls) > 0
 	}, time.Second, 100*time.Millisecond)
+
+	metrics.lock.Lock()
+	defer metrics.lock.Unlock()
+
+	foundPush := false
+	for _, key := range metrics.pushToSeriesCalls {
+		if strings.HasSuffix(key, "response_time") {
+			foundPush = true
+			break
+		}
+	}
+	assert.True(t, foundPush, "PushToSeries should register key with suffix response_time")
+
+	foundStatus := false
+	for _, key := range metrics.incrCounterCalls {
+		if strings.HasSuffix(key, "status.200") {
+			foundStatus = true
+			break
+		}
+	}
+	assert.True(t, foundStatus, "IncrCounter should register key with suffix status.200")
+
+	foundAttrs := false
+	for _, call := range metrics.incrCounterWithAttrsCalls {
+		if strings.HasSuffix(call.key, "total") &&
+			call.attrs["status"] == "200" &&
+			call.attrs["host"] != "" {
+			foundAttrs = true
+			break
+		}
+	}
+	assert.True(t, foundAttrs, "IncrCounterWithAttrs should register correct attributes and key with suffix total")
+}
+
+func TestHTTPClient_Metrics_Errors(t *testing.T) {
+	t.Run("circuit open error", func(t *testing.T) {
+		metrics := &mockMetrics{}
+		client := httpclient.NewHTTPClient(
+			&httpclient.LoggerAdapter{Writer: io.Discard},
+			httpclient.WithMetrics(metrics),
+			httpclient.WithChainCallback(func(fn func() (*httpclient.Response, error)) (*httpclient.Response, error) {
+				return nil, httpclient.ErrCircuitOpen
+			}),
+		)
+		_, _ = client.NewRequest().Get("/test-circuit-open")
+		time.Sleep(50 * time.Millisecond)
+		metrics.lock.Lock()
+		defer metrics.lock.Unlock()
+		found := false
+		for _, call := range metrics.incrCounterCalls {
+			if strings.HasSuffix(call, "circuit_open") {
+				found = true
+				break
+			}
+		}
+		assert.True(t, found, "Should increment circuit_open counter on ErrCircuitOpen")
+	})
+
+	t.Run("generic error", func(t *testing.T) {
+		metrics := &mockMetrics{}
+		client := httpclient.NewHTTPClient(
+			&httpclient.LoggerAdapter{Writer: io.Discard},
+			httpclient.WithMetrics(metrics),
+			httpclient.WithChainCallback(func(fn func() (*httpclient.Response, error)) (*httpclient.Response, error) {
+				return nil, assert.AnError
+			}),
+		)
+		_, _ = client.NewRequest().Get("/test-generic-error")
+		time.Sleep(50 * time.Millisecond)
+		metrics.lock.Lock()
+		defer metrics.lock.Unlock()
+		foundError := false
+		foundAttr := false
+		for _, call := range metrics.incrCounterCalls {
+			if strings.HasSuffix(call, "errors") {
+				foundError = true
+				break
+			}
+		}
+		for _, call := range metrics.incrCounterWithAttrsCalls {
+			if val, ok := call.attrs["error"]; ok && val == assert.AnError.Error() {
+				foundAttr = true
+				break
+			}
+		}
+		assert.True(t, foundError, "Should increment errors counter on generic error")
+		assert.True(t, foundAttr, "Should add error attribute on generic error")
+	})
 }
diff --git a/request.go b/request.go
index 9c2cb13..478489e 100644
--- a/request.go
+++ b/request.go
@@ -150,7 +150,7 @@ func registerMetrics(key string, metrics Metrics, f func() (*Response, error)) (
 
 	if metrics != nil {
 		go func(resp *Response, err error) {
-			var attrs map[string]string
+			attrs := map[string]string{}
 			if resp != nil {
 				attrs = map[string]string{
 					"host": resp.Request().HostURL().Host,
@@ -167,6 +167,7 @@ func registerMetrics(key string, metrics Metrics, f func() (*Response, error)) (
 					metrics.IncrCounter(fmt.Sprintf("%s.%s", key, "circuit_open"))
 				} else {
 					metrics.IncrCounter(fmt.Sprintf("%s.%s", key, "errors"))
+					attrs["error"] = err.Error()
 				}
 			}
 			metrics.IncrCounterWithAttrs(fmt.Sprintf("%s.%s", key, "total"), attrs)