diff --git a/tests/timmy/test_memory_system.py b/tests/timmy/test_memory_system.py
index 80ff2334..40590341 100644
--- a/tests/timmy/test_memory_system.py
+++ b/tests/timmy/test_memory_system.py
@@ -7,6 +7,8 @@ import pytest
 from timmy.memory_system import (
     HotMemory,
     MemorySystem,
+    jot_note,
+    log_decision,
     reset_memory_system,
     store_last_reflection,
 )
@@ -246,3 +248,81 @@ class TestStoreLastReflection:
             result = recall_last_reflection()
 
         assert result is None
+
+
+class TestJotNote:
+    """Tests for jot_note() artifact tool."""
+
+    def test_saves_note_file(self, tmp_path):
+        """jot_note creates a markdown file with title and body."""
+        notes_dir = tmp_path / "notes"
+        with patch("timmy.memory_system.NOTES_DIR", notes_dir):
+            result = jot_note("My Title", "Some body text")
+
+        assert "Note saved:" in result
+        files = list(notes_dir.glob("*.md"))
+        assert len(files) == 1
+        content = files[0].read_text()
+        assert "# My Title" in content
+        assert "Some body text" in content
+        assert "Created:" in content
+
+    def test_slug_in_filename(self, tmp_path):
+        """Filename contains a slug derived from the title."""
+        notes_dir = tmp_path / "notes"
+        with patch("timmy.memory_system.NOTES_DIR", notes_dir):
+            jot_note("Hello World!", "body")
+
+        files = list(notes_dir.glob("*.md"))
+        assert "hello-world" in files[0].name
+
+    def test_rejects_empty_title(self):
+        """jot_note rejects empty title."""
+        assert "title is empty" in jot_note("", "body")
+        assert "title is empty" in jot_note("   ", "body")
+
+    def test_rejects_empty_body(self):
+        """jot_note rejects empty body."""
+        assert "body is empty" in jot_note("title", "")
+        assert "body is empty" in jot_note("title", "   ")
+
+
+class TestLogDecision:
+    """Tests for log_decision() artifact tool."""
+
+    def test_creates_decision_log(self, tmp_path):
+        """log_decision creates the log file and appends an entry."""
+        log_file = tmp_path / "decisions.md"
+        with patch("timmy.memory_system.DECISION_LOG", log_file):
+            result = log_decision("Use SQLite for storage")
+
+        assert "Decision logged:" in result
+        content = log_file.read_text()
+        assert "# Decision Log" in content
+        assert "Use SQLite for storage" in content
+
+    def test_appends_multiple_decisions(self, tmp_path):
+        """Multiple decisions are appended to the same file."""
+        log_file = tmp_path / "decisions.md"
+        with patch("timmy.memory_system.DECISION_LOG", log_file):
+            log_decision("First decision")
+            log_decision("Second decision")
+
+        content = log_file.read_text()
+        assert "First decision" in content
+        assert "Second decision" in content
+
+    def test_includes_rationale(self, tmp_path):
+        """Rationale is included when provided."""
+        log_file = tmp_path / "decisions.md"
+        with patch("timmy.memory_system.DECISION_LOG", log_file):
+            log_decision("Use Redis", "Fast in-memory cache")
+
+        content = log_file.read_text()
+        assert "Use Redis" in content
+        assert "Fast in-memory cache" in content
+
+    def test_rejects_empty_decision(self):
+        """log_decision rejects empty decision string."""
+        assert "decision is empty" in log_decision("")
+        assert "decision is empty" in log_decision("   ")