enhanced infos

pkg/tools/filesystem.go

@@ -534,6 +534,12 @@ func (t *ReadFileLinesTool) Execute(ctx context.Context, args map[string]any) *T
 	if startLine < 1 {
 		return ErrorResult("start_line must be >= 1")
 	}
+	if _, exists := args["offset"]; exists {
+		return ErrorResult("offset is not supported in line mode; use start_line")
+	}
+	if _, exists := args["length"]; exists {
+		return ErrorResult("length is not supported in line mode; use max_lines")
+	}
 
 	limit := int64(-1)
 	if raw, exists := args["max_lines"]; exists && raw != nil {
@@ -644,19 +650,28 @@ func (t *ReadFileLinesTool) Execute(ctx context.Context, args map[string]any) *T
 	switch {
 	case lineTruncated:
 		header += fmt.Sprintf(
-			"\n[TRUNCATED - line %d exceeded the %d byte read budget and was cut mid-line.",
+			"\n[TRUNCATED - line %d exceeded the %d byte read budget and was cut mid-line.]",
 			endLine,
 			t.maxSize,
 		)
 	case byteBudgetTruncated:
+		if limit > 0 {
+			header += fmt.Sprintf(
+				"\n[TRUNCATED - byte budget reached. Call read_file again with start_line=%d and max_lines=%d to continue at the next line.]",
+				startLine+linesRead,
+				limit,
+			)
+		} else {
 			header += fmt.Sprintf(
 				"\n[TRUNCATED - byte budget reached. Call read_file again with start_line=%d to continue at the next line.]",
 				startLine+linesRead,
 			)
+		}
 	case !reachedEOF && limit > 0 && linesRead >= limit:
 		header += fmt.Sprintf(
-			"\n[PARTIAL - more content remains. Call read_file again with start_line=%d to continue.]",
+			"\n[PARTIAL - more content remains. Call read_file again with start_line=%d and max_lines=%d to continue.]",
 			startLine+linesRead,
+			limit,
 		)
 	default:
 		header += "\n[END OF FILE - no further content.]"

pkg/tools/filesystem_test.go

@@ -897,6 +897,9 @@ func TestReadFileLinesTool_ChunkedReading(t *testing.T) {
 	if !strings.Contains(result1.ForLLM, "start_line=3") {
 		t.Fatalf("expected continuation start_line=3, got: %s", result1.ForLLM)
 	}
+	if !strings.Contains(result1.ForLLM, "max_lines=2") {
+		t.Fatalf("expected continuation max_lines=2, got: %s", result1.ForLLM)
+	}
 
 	result2 := tool.Execute(context.Background(), map[string]any{
 		"path":       testFile,
@@ -912,6 +915,9 @@ func TestReadFileLinesTool_ChunkedReading(t *testing.T) {
 	if !strings.Contains(result2.ForLLM, "start_line=5") {
 		t.Fatalf("expected continuation start_line=5, got: %s", result2.ForLLM)
 	}
+	if !strings.Contains(result2.ForLLM, "max_lines=2") {
+		t.Fatalf("expected continuation max_lines=2, got: %s", result2.ForLLM)
+	}
 
 	result3 := tool.Execute(context.Background(), map[string]any{
 		"path":       testFile,
@@ -1042,6 +1048,52 @@ func TestReadFileLinesTool_RegistryValidationSupportsMaxLinesAndRejectsLimit(t *
 	}
 }
 
+func TestReadFileLinesTool_RejectsOffset(t *testing.T) {
+	tmpDir := t.TempDir()
+	testFile := filepath.Join(tmpDir, "legacy_offset.txt")
+
+	err := os.WriteFile(testFile, []byte("line 1\nline 2\n"), 0o644)
+	if err != nil {
+		t.Fatalf("Failed to write test file: %v", err)
+	}
+
+	tool := NewReadFileLinesTool(tmpDir, false, MaxReadFileSize)
+	result := tool.Execute(context.Background(), map[string]any{
+		"path":       testFile,
+		"start_line": 1,
+		"offset":     1,
+	})
+	if !result.IsError {
+		t.Fatalf("expected offset to be rejected, got success: %s", result.ForLLM)
+	}
+	if !strings.Contains(result.ForLLM, "offset is not supported in line mode; use start_line") {
+		t.Fatalf("unexpected error for offset in line mode: %s", result.ForLLM)
+	}
+}
+
+func TestReadFileLinesTool_RejectsLength(t *testing.T) {
+	tmpDir := t.TempDir()
+	testFile := filepath.Join(tmpDir, "legacy_length.txt")
+
+	err := os.WriteFile(testFile, []byte("line 1\nline 2\n"), 0o644)
+	if err != nil {
+		t.Fatalf("Failed to write test file: %v", err)
+	}
+
+	tool := NewReadFileLinesTool(tmpDir, false, MaxReadFileSize)
+	result := tool.Execute(context.Background(), map[string]any{
+		"path":       testFile,
+		"start_line": 1,
+		"length":     1,
+	})
+	if !result.IsError {
+		t.Fatalf("expected length to be rejected, got success: %s", result.ForLLM)
+	}
+	if !strings.Contains(result.ForLLM, "length is not supported in line mode; use max_lines") {
+		t.Fatalf("unexpected error for length in line mode: %s", result.ForLLM)
+	}
+}
+
 func TestReadFileLinesTool_BinaryFileRejected(t *testing.T) {
 	tmpDir := t.TempDir()
 	testFile := filepath.Join(tmpDir, "binary.dat")