diff --git a/cmd/apiutil/client.go b/cmd/apiutil/client.go
index 3ebf8f8..1541fb9 100644
--- a/cmd/apiutil/client.go
+++ b/cmd/apiutil/client.go
@@ -76,13 +76,23 @@ func RawGet(ctx context.Context, client *api.APIClient, path string, params url.
 	return body, nil
 }
 
+// NormalizeServerURL trims trailing slashes from raw and appends /api/v1 exactly
+// once. Returns an empty string when raw is blank or all slashes.
+func NormalizeServerURL(raw string) string {
+	s := strings.TrimRight(raw, "/")
+	if s == "" {
+		return ""
+	}
+	if !strings.HasSuffix(s, "/api/v1") {
+		s += "/api/v1"
+	}
+	return s
+}
+
 // NewAPIClientWithKeyAndTransport is the base constructor used by all other helpers.
 func NewAPIClientWithKeyAndTransport(apiKey string, transport http.RoundTripper) *api.APIClient {
 	configuration := api.NewConfiguration()
-	serverURL := viper.GetString("seerr.server")
-	if !strings.HasSuffix(serverURL, "/api/v1") {
-		serverURL = strings.TrimSuffix(serverURL, "/") + "/api/v1"
-	}
+	serverURL := NormalizeServerURL(viper.GetString("seerr.server"))
 	configuration.Servers = api.ServerConfigurations{{URL: serverURL, Description: "Configured Server"}}
 	key := apiKey
 	if key == "" {
diff --git a/cmd/mcp/serve.go b/cmd/mcp/serve.go
index a5c79d1..266e54a 100644
--- a/cmd/mcp/serve.go
+++ b/cmd/mcp/serve.go
@@ -7,6 +7,8 @@ import (
 	"net/http"
 	"strings"
 
+	"seerr-cli/cmd/apiutil"
+
 	"github.com/mark3labs/mcp-go/server"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
@@ -75,6 +77,10 @@ func runServe(_ *cobra.Command, args []string) error {
 		return err
 	}
 
+	if err := ValidateServeConfig(); err != nil {
+		return err
+	}
+
 	if transport == "http" && authToken == "" && routeToken == "" && !noAuth {
 		return fmt.Errorf("HTTP transport requires --auth-token, --route-token, or --no-auth (insecure) to be set explicitly")
 	}
@@ -185,6 +191,16 @@ func runServe(_ *cobra.Command, args []string) error {
 	}
 }
 
+// ValidateServeConfig checks that the Seerr server URL is configured. It is
+// exported so that tests can verify the fail-fast behaviour without starting
+// the server.
+func ValidateServeConfig() error {
+	if apiutil.NormalizeServerURL(viper.GetString("seerr.server")) == "" {
+		return fmt.Errorf("seerr.server is not configured; set it with --server <url> or add seerr.server to ~/.seerr-cli.yaml")
+	}
+	return nil
+}
+
 // HealthCheckHandler responds to GET /health with a JSON status payload.
 // It is exported so that it can be tested directly from the tests package.
 func HealthCheckHandler(w http.ResponseWriter, r *http.Request) {
diff --git a/tests/apiutil_client_test.go b/tests/apiutil_client_test.go
new file mode 100644
index 0000000..ba7d68b
--- /dev/null
+++ b/tests/apiutil_client_test.go
@@ -0,0 +1,58 @@
+package tests
+
+import (
+	"testing"
+
+	"seerr-cli/cmd/apiutil"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNormalizeServerURL(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{
+			name:  "bare host",
+			input: "https://host",
+			want:  "https://host/api/v1",
+		},
+		{
+			name:  "trailing slash",
+			input: "https://host/",
+			want:  "https://host/api/v1",
+		},
+		{
+			name:  "multiple trailing slashes",
+			input: "https://host///",
+			want:  "https://host/api/v1",
+		},
+		{
+			name:  "already has api/v1",
+			input: "https://host/api/v1",
+			want:  "https://host/api/v1",
+		},
+		{
+			name:  "api/v1 with trailing slash",
+			input: "https://host/api/v1/",
+			want:  "https://host/api/v1",
+		},
+		{
+			name:  "empty string",
+			input: "",
+			want:  "",
+		},
+		{
+			name:  "only slashes",
+			input: "///",
+			want:  "",
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.want, apiutil.NormalizeServerURL(tc.input))
+		})
+	}
+}
diff --git a/tests/mcp_serve_validation_test.go b/tests/mcp_serve_validation_test.go
new file mode 100644
index 0000000..fd41a47
--- /dev/null
+++ b/tests/mcp_serve_validation_test.go
@@ -0,0 +1,58 @@
+package tests
+
+import (
+	"testing"
+
+	"github.com/spf13/viper"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	cmdmcp "seerr-cli/cmd/mcp"
+)
+
+func TestMCPServeFailsFastWithoutSeerrServer(t *testing.T) {
+	original := viper.GetString("seerr.server")
+	t.Cleanup(func() { viper.Set("seerr.server", original) })
+
+	tests := []struct {
+		name        string
+		seerrServer string
+		wantErr     bool
+		errContains string
+	}{
+		{
+			name:        "missing server returns error",
+			seerrServer: "",
+			wantErr:     true,
+			errContains: "seerr.server",
+		},
+		{
+			name:        "only slashes returns error",
+			seerrServer: "///",
+			wantErr:     true,
+			errContains: "seerr.server",
+		},
+		{
+			name:        "valid server passes validation",
+			seerrServer: "http://localhost:5055",
+			wantErr:     false,
+		},
+		{
+			name:        "valid server with trailing slash passes validation",
+			seerrServer: "http://localhost:5055/",
+			wantErr:     false,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			viper.Set("seerr.server", tc.seerrServer)
+			err := cmdmcp.ValidateServeConfig()
+			if tc.wantErr {
+				require.Error(t, err)
+				assert.Contains(t, err.Error(), tc.errContains)
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}