diff --git a/mcp/streamable_headers.go b/mcp/streamable_headers.go
index 3989c016..7d06399b 100644
--- a/mcp/streamable_headers.go
+++ b/mcp/streamable_headers.go
@@ -262,6 +262,12 @@ func filterValidTools(logger *slog.Logger, tools []*Tool) []*Tool {
 	logger = ensureLogger(logger)
 	result := make([]*Tool, 0, len(tools))
 	for _, tool := range tools {
+		// A nil tool (e.g. from a malformed "tools":[null] response) is
+		// invalid; exclude it instead of dereferencing it.
+		if tool == nil {
+			logger.Error("excluding nil tool from tools/list")
+			continue
+		}
 		if err := validateParamHeaderAnnotations(tool); err != nil {
 			logger.Error("excluding tool from tools/list", "tool", tool.Name, "error", err)
 			continue
diff --git a/mcp/streamable_headers_test.go b/mcp/streamable_headers_test.go
index 52d52447..def7ad1f 100644
--- a/mcp/streamable_headers_test.go
+++ b/mcp/streamable_headers_test.go
@@ -969,6 +969,15 @@ func TestFilterValidTools(t *testing.T) {
 		t.Errorf("filterValidTools returned [%s, %s, %s, %s], want [valid, plain, nested-valid, valid-jsonschema]",
 			result[0].Name, result[1].Name, result[2].Name, result[3].Name)
 	}
+
+	// Regression for #1119: a malformed "tools":[null] response must not panic;
+	// nil tools are treated as invalid and excluded.
+	if got := filterValidTools(nil, []*Tool{nil}); len(got) != 0 {
+		t.Errorf("filterValidTools([nil]) returned %d tools, want 0", len(got))
+	}
+	if got := filterValidTools(nil, []*Tool{nil, valid, nil}); len(got) != 1 || got[0].Name != "valid" {
+		t.Errorf("filterValidTools([nil, valid, nil]) = %d tools, want [valid]", len(got))
+	}
 }
 
 func TestSetStandardHeadersWithParamHeaders(t *testing.T) {