diff --git a/environments/text_2048/src/hud_controller/setup/board.py b/environments/text_2048/src/hud_controller/setup/board.py
index 52a521fb..1e99ce77 100644
--- a/environments/text_2048/src/hud_controller/setup/board.py
+++ b/environments/text_2048/src/hud_controller/setup/board.py
@@ -1,21 +1,86 @@
 """Board-size setup function for 2048."""
 
-from mcp.types import TextContent, ContentBlock
+from __future__ import annotations
+
+import json
+from contextlib import contextmanager
+from typing import Any
+
+from mcp.types import ContentBlock, TextContent
+
+try:
+    from hud.telemetry import trace
+except ModuleNotFoundError:  # pragma: no cover - optional dependency safeguard
+
+    @contextmanager
+    def trace(*_args: Any, **_kwargs: Any) -> Any:  # type: ignore[misc]
+        yield
+
 from . import setup
 
+DEFAULT_BOARD_SIZE = 4
+MIN_BOARD_SIZE = 3
+MAX_BOARD_SIZE = 8
+
+
+def _normalize_board_size(value: Any) -> tuple[int, str | None]:
+    """Convert ``value`` into a clamped integer plus a note if coercion was needed."""
+    note: str | None = None
+    try:
+        size = int(value)
+    except (TypeError, ValueError):
+        size = DEFAULT_BOARD_SIZE
+        note = (
+            f"Invalid board size {value!r}; defaulting to {DEFAULT_BOARD_SIZE}."
+        )
+        return size, note
+
+    if size < MIN_BOARD_SIZE:
+        note = (
+            f"Requested board size {size} is below {MIN_BOARD_SIZE}; "
+            f"using {MIN_BOARD_SIZE}."
+        )
+        return MIN_BOARD_SIZE, note
+
+    if size > MAX_BOARD_SIZE:
+        note = (
+            f"Requested board size {size} exceeds {MAX_BOARD_SIZE}; "
+            f"using {MAX_BOARD_SIZE}."
+        )
+        return MAX_BOARD_SIZE, note
+
+    return size, None
+
 
 @setup.tool("board")
-async def setup_board(board_size: int = 4) -> list[ContentBlock]:
+async def setup_board(board_size: int = DEFAULT_BOARD_SIZE) -> list[ContentBlock]:
     """Initialize a new game with the specified board size."""
+    normalized_size, validation_note = _normalize_board_size(board_size)
     game = setup.env
-    game.reset(size=board_size)
 
-    # Get the initial board state to show the agent
-    board_display = game.get_board_ascii()
+    with trace(
+        "text-2048 setup",
+        attrs={
+            "requested_board_size": board_size,
+            "board_size": normalized_size,
+            "validation_note": validation_note or "",
+        },
+    ):
+        game.reset(size=normalized_size)
+        board_display = game.get_board_ascii()
+        state_payload = {
+            "requested_board_size": board_size,
+            "board_size": normalized_size,
+            "state": game.get_state(),
+        }
+
+    lines = [f"{normalized_size}x{normalized_size} game initialized"]
+    if validation_note:
+        lines.append(validation_note)
+    lines.append("")
+    lines.append(board_display)
 
-    # Return the initial board display
     return [
-        TextContent(
-            text=f"{board_size}x{board_size} game initialized\n\n{board_display}", type="text"
-        )
+        TextContent(text="\n".join(lines), type="text"),
+        TextContent(text=json.dumps(state_payload), type="text"),
     ]
diff --git a/hud/tests/test_text_2048_setup_board.py b/hud/tests/test_text_2048_setup_board.py
new file mode 100644
index 00000000..d2e18909
--- /dev/null
+++ b/hud/tests/test_text_2048_setup_board.py
@@ -0,0 +1,86 @@
+"""Tests for the text-2048 setup board tool."""
+
+from __future__ import annotations
+
+import json
+import sys
+from contextlib import contextmanager
+from pathlib import Path
+
+import pytest
+
+# Ensure the environment package is importable from the repository root
+REPO_ROOT = Path(__file__).resolve().parents[2]
+ENV_SRC = REPO_ROOT / "environments" / "text_2048" / "src"
+if str(ENV_SRC) not in sys.path:
+    sys.path.append(str(ENV_SRC))
+
+from hud_controller.setup import board as board_module  # noqa: E402
+
+
+class DummyGame:
+    """Minimal game stub for exercising setup_board."""
+
+    def __init__(self) -> None:
+        self.size = 0
+        self.reset_calls: list[int] = []
+
+    def reset(self, size: int = 4) -> None:
+        self.size = size
+        self.reset_calls.append(size)
+
+    def get_board_ascii(self) -> str:
+        return f"{self.size}x{self.size} board"
+
+    def get_state(self) -> dict:
+        return {
+            "board": [[self.size]],
+            "score": 0,
+            "moves": 0,
+            "game_over": False,
+            "won": False,
+            "highest_tile": self.size,
+        }
+
+
+@pytest.fixture(autouse=True)
+def stub_trace(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Replace telemetry trace context manager with a no-op."""
+
+    @contextmanager
+    def _noop_trace(*args, **kwargs):  # noqa: ANN001, ANN003
+        yield
+
+    monkeypatch.setattr(board_module, "trace", _noop_trace)
+
+
+@pytest.mark.asyncio
+async def test_setup_board_returns_ascii_and_json(monkeypatch: pytest.MonkeyPatch) -> None:
+    game = DummyGame()
+    monkeypatch.setattr(board_module.setup, "env", game, raising=False)
+
+    result = await board_module.setup_board.fn(board_size=5)
+    assert len(result) == 2
+
+    ascii_block, json_block = result
+    assert "5x5 game initialized" in ascii_block.text
+
+    payload = json.loads(json_block.text)
+    assert payload["board_size"] == 5
+    assert payload["state"]["board"] == [[5]]
+
+
+@pytest.mark.asyncio
+async def test_setup_board_clamps_out_of_range_values(monkeypatch: pytest.MonkeyPatch) -> None:
+    game = DummyGame()
+    monkeypatch.setattr(board_module.setup, "env", game, raising=False)
+
+    result = await board_module.setup_board.fn(board_size=99)
+    ascii_block, json_block = result
+
+    assert str(board_module.MAX_BOARD_SIZE) in ascii_block.text
+    assert "using" in ascii_block.text.lower()
+
+    payload = json.loads(json_block.text)
+    assert payload["board_size"] == board_module.MAX_BOARD_SIZE
+    assert payload["requested_board_size"] == 99