diff --git a/patchwork/cli.py b/patchwork/cli.py
index 4955c76..8847ca2 100644
--- a/patchwork/cli.py
+++ b/patchwork/cli.py
@@ -1,10 +1,16 @@
+import argparse
 import asyncio
+import json
+import logging
+from collections.abc import AsyncIterable
 
 from dotenv import load_dotenv
+from pydantic_ai import FunctionToolCallEvent, RunContext
 from rich.console import Console
 
 from patchwork.agent import agent
 from patchwork.deps import PatchworkDeps
+from patchwork.logging_config import setup_logging
 from patchwork.midi import MidiConnection
 from patchwork.patch_library import PatchLibrary
 from patchwork.synth_definitions import load_synth_definitions
@@ -12,7 +18,28 @@
 console = Console()
 
 
-async def main():
+def _make_event_handler(verbose: bool, logger: logging.Logger):
+    """Return an event_stream_handler that logs tool calls."""
+
+    async def handle_events(ctx: RunContext[PatchworkDeps], events: AsyncIterable) -> None:
+        async for event in events:
+            if isinstance(event, FunctionToolCallEvent):
+                tool_name = event.part.tool_name
+                logger.info("tool call: %s", tool_name)
+
+                if verbose:
+                    try:
+                        args = event.part.args_as_dict()
+                    except Exception:
+                        args = event.part.args
+                    logger.debug("tool args: %s %s", tool_name, json.dumps(args, default=str))
+                    console.print(f"[dim]⚙ {tool_name}[/dim]")
+
+    return handle_events
+
+
+async def main(verbose: bool = False):
+    logger = setup_logging(verbose=verbose)
     midi = MidiConnection()
     synths = load_synth_definitions()
 
@@ -27,6 +54,8 @@ async def main():
             console.print("[dim]no synth definitions found in synths/[/dim]\n")
         message_history = []
 
+        event_handler = _make_event_handler(verbose, logger)
+
         try:
             while True:
                 try:
@@ -44,7 +73,10 @@ async def main():
 
                 try:
                     async with agent.run_stream(
-                        user_input, message_history=message_history, deps=deps
+                        user_input,
+                        message_history=message_history,
+                        deps=deps,
+                        event_stream_handler=event_handler,
                     ) as result:
                         async for chunk in result.stream_text(delta=True):
                             console.print(chunk, end="", markup=False, highlight=False)
@@ -52,6 +84,7 @@ async def main():
 
                     message_history = result.all_messages()
                 except Exception as e:
+                    logger.exception("Error during agent run")
                     console.print(f"\n[bold red]error:[/bold red] {e}")
         finally:
             midi.close()
@@ -59,7 +92,12 @@ async def main():
 
 def main_cli():
     load_dotenv()
-    asyncio.run(main())
+
+    parser = argparse.ArgumentParser(description="patchwork — synth research agent")
+    parser.add_argument("-v", "--verbose", action="store_true", help="enable verbose logging")
+    args = parser.parse_args()
+
+    asyncio.run(main(verbose=args.verbose))
 
 
 if __name__ == "__main__":
diff --git a/patchwork/logging_config.py b/patchwork/logging_config.py
new file mode 100644
index 0000000..0510676
--- /dev/null
+++ b/patchwork/logging_config.py
@@ -0,0 +1,25 @@
+import logging
+import sys
+
+
+def setup_logging(verbose: bool = False) -> logging.Logger:
+    """Configure the patchwork logger. Idempotent — safe to call multiple times.
+
+    Always updates the handler level to match the current ``verbose`` setting,
+    but never adds duplicate handlers.
+    """
+    logger = logging.getLogger("patchwork")
+    level = logging.DEBUG if verbose else logging.INFO
+
+    if logger.handlers:
+        logger.handlers[0].setLevel(level)
+        return logger
+
+    handler = logging.StreamHandler(sys.stderr)
+    handler.setLevel(level)
+    handler.setFormatter(logging.Formatter("%(asctime)s %(name)s %(levelname)s %(message)s"))
+
+    logger.setLevel(logging.DEBUG)
+    logger.addHandler(handler)
+
+    return logger
diff --git a/tests/test_logging_config.py b/tests/test_logging_config.py
new file mode 100644
index 0000000..08d1931
--- /dev/null
+++ b/tests/test_logging_config.py
@@ -0,0 +1,44 @@
+import logging
+
+from patchwork.logging_config import setup_logging
+
+
+class TestSetupLogging:
+    def setup_method(self):
+        """Remove any existing patchwork logger handlers before each test."""
+        logger = logging.getLogger("patchwork")
+        logger.handlers.clear()
+
+    def test_returns_logger(self):
+        logger = setup_logging()
+        assert isinstance(logger, logging.Logger)
+        assert logger.name == "patchwork"
+
+    def test_adds_stderr_handler(self):
+        logger = setup_logging()
+        assert len(logger.handlers) == 1
+        assert isinstance(logger.handlers[0], logging.StreamHandler)
+
+    def test_default_handler_level_is_info(self):
+        logger = setup_logging(verbose=False)
+        assert logger.handlers[0].level == logging.INFO
+
+    def test_verbose_handler_level_is_debug(self):
+        logger = setup_logging(verbose=True)
+        assert logger.handlers[0].level == logging.DEBUG
+
+    def test_idempotent_no_duplicate_handlers(self):
+        logger = setup_logging()
+        setup_logging()
+        assert len(logger.handlers) == 1
+
+    def test_logger_level_is_debug(self):
+        logger = setup_logging()
+        assert logger.level == logging.DEBUG
+
+    def test_subsequent_call_updates_handler_level(self):
+        logger = setup_logging(verbose=False)
+        assert logger.handlers[0].level == logging.INFO
+        setup_logging(verbose=True)
+        assert logger.handlers[0].level == logging.DEBUG
+        assert len(logger.handlers) == 1
diff --git a/tests/test_tool_logging.py b/tests/test_tool_logging.py
new file mode 100644
index 0000000..9db451e
--- /dev/null
+++ b/tests/test_tool_logging.py
@@ -0,0 +1,98 @@
+import logging
+from unittest.mock import MagicMock
+
+import pytest
+
+from patchwork.cli import _make_event_handler
+
+
+def _make_mock_tool_call_event(tool_name: str, args: dict | None = None):
+    """Create a mock FunctionToolCallEvent."""
+    from pydantic_ai import FunctionToolCallEvent
+    from pydantic_ai.messages import ToolCallPart
+
+    part = ToolCallPart(tool_name=tool_name, args=args or {})
+    return FunctionToolCallEvent(part=part)
+
+
+async def _to_async_iterable(items):
+    for item in items:
+        yield item
+
+
+@pytest.fixture
+def logger():
+    log = logging.getLogger("patchwork.test_tool_logging")
+    log.handlers.clear()
+    log.setLevel(logging.DEBUG)
+    handler = logging.StreamHandler()
+    handler.setLevel(logging.DEBUG)
+    log.addHandler(handler)
+    return log
+
+
+class TestToolCallEventHandler:
+    @pytest.mark.asyncio
+    async def test_logs_tool_name(self, logger, caplog):
+        handler = _make_event_handler(verbose=False, logger=logger)
+        event = _make_mock_tool_call_event("send_cc")
+        ctx = MagicMock()
+
+        with caplog.at_level(logging.INFO, logger=logger.name):
+            await handler(ctx, _to_async_iterable([event]))
+
+        assert any("send_cc" in record.message for record in caplog.records)
+
+    @pytest.mark.asyncio
+    async def test_verbose_logs_args(self, logger, caplog):
+        handler = _make_event_handler(verbose=True, logger=logger)
+        args = {"synth_id": "minitaur", "param": "cutoff", "value": 64}
+        event = _make_mock_tool_call_event("send_cc", args)
+        ctx = MagicMock()
+
+        with caplog.at_level(logging.DEBUG, logger=logger.name):
+            await handler(ctx, _to_async_iterable([event]))
+
+        debug_msgs = [r.message for r in caplog.records if r.levelno == logging.DEBUG]
+        assert any("minitaur" in msg for msg in debug_msgs)
+
+    @pytest.mark.asyncio
+    async def test_ignores_non_tool_events(self, logger, caplog):
+        handler = _make_event_handler(verbose=False, logger=logger)
+        ctx = MagicMock()
+
+        # A non-FunctionToolCallEvent object
+        other_event = MagicMock()
+        other_event.event_kind = "part_start"
+
+        with caplog.at_level(logging.INFO, logger=logger.name):
+            await handler(ctx, _to_async_iterable([other_event]))
+
+        tool_records = [r for r in caplog.records if "tool call" in r.message]
+        assert len(tool_records) == 0
+
+    @pytest.mark.asyncio
+    async def test_handles_multiple_events(self, logger, caplog):
+        handler = _make_event_handler(verbose=False, logger=logger)
+        events = [
+            _make_mock_tool_call_event("list_synths"),
+            _make_mock_tool_call_event("send_cc"),
+        ]
+        ctx = MagicMock()
+
+        with caplog.at_level(logging.INFO, logger=logger.name):
+            await handler(ctx, _to_async_iterable(events))
+
+        tool_records = [r for r in caplog.records if "tool call" in r.message]
+        assert len(tool_records) == 2
+
+    @pytest.mark.asyncio
+    async def test_non_verbose_does_not_print_tool_indicator(self, logger, capsys):
+        handler = _make_event_handler(verbose=False, logger=logger)
+        event = _make_mock_tool_call_event("send_cc")
+        ctx = MagicMock()
+
+        await handler(ctx, _to_async_iterable([event]))
+
+        captured = capsys.readouterr()
+        assert "⚙" not in captured.out