Avoid blocking the event loop in markitdown-mcp

packages/markitdown-mcp/src/markitdown_mcp/__main__.py

@@ -1,3 +1,4 @@
+import asyncio
 import contextlib
 import sys
 import os
@@ -20,7 +21,11 @@
 @mcp.tool()
 async def convert_to_markdown(uri: str) -> str:
     """Convert a resource described by an http:, https:, file: or data: URI to markdown"""
-    return MarkItDown(enable_plugins=check_plugins_enabled()).convert_uri(uri).markdown
+    result = await asyncio.to_thread(
+        MarkItDown(enable_plugins=check_plugins_enabled()).convert_uri,
+        uri,
+    )
+    return result.markdown
 
 
 def check_plugins_enabled() -> bool:

packages/markitdown-mcp/tests/test_main.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+
+import threading
+from types import SimpleNamespace
+
+import pytest
+
+from markitdown_mcp import __main__ as main
+
+
+@pytest.mark.anyio
+async def test_convert_to_markdown_runs_conversion_off_event_loop(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    event_loop_thread = threading.get_ident()
+    conversion_thread: list[int] = []
+
+    class FakeMarkItDown:
+        def __init__(self, *, enable_plugins: bool) -> None:
+            self.enable_plugins = enable_plugins
+
+        def convert_uri(self, uri: str) -> SimpleNamespace:
+            conversion_thread.append(threading.get_ident())
+            return SimpleNamespace(markdown=f"converted:{uri}")
+
+    monkeypatch.setattr(main, "MarkItDown", FakeMarkItDown)
+
+    result = await main.convert_to_markdown("https://example.com/test.txt")
+
+    assert result == "converted:https://example.com/test.txt"
+    assert conversion_thread == [conversion_thread[0]]
+    assert conversion_thread[0] != event_loop_thread