StructuredTool does not support sync invocation.

---

def _run(
    self,
    *args: Any,
    config: RunnableConfig,
    run_manager: CallbackManagerForToolRun | None = None,
    **kwargs: Any,
) -> Any:
    if self.func:
        if run_manager and signature(self.func).parameters.get("callbacks"):
            kwargs["callbacks"] = run_manager.get_child()
        if config_param := _get_runnable_config_param(self.func):
            kwargs[config_param] = config
        return self.func(*args, **kwargs)
    msg = "StructuredTool does not support sync invocation."
    raise NotImplementedError(msg)

---

async def ainvoke(
    self,
    input: str | dict | ToolCall,
    config: RunnableConfig | None = None,
    **kwargs: Any,
) -> Any:
    if not self.coroutine:
        # Fallback to thread pool for sync tools
        return await run_in_executor(config, self.invoke, input, config, **kwargs)
    return await super().ainvoke(input, config, **kwargs)

---

def _run(self, *args, **kwargs) -> Any:
    if self.func:
        return self.func(*args, **kwargs)
    if self.coroutine:
        # Fallback: Execute async coroutine in event loop
        loop = asyncio.get_event_loop()
        return loop.run_until_complete(self.coroutine(*args, **kwargs))
    raise NotImplementedError(msg)

---

from langchain_mcp_adapters.tools import load_mcp_tools
from langchain_mcp_adapters.sessions import StdioConnection

# Load an MCP tool (which has coroutine but no func)
conn = StdioConnection(
    transport='stdio',
    command='npx',
    args=['@modelcontextprotocol/server-filesystem', '/tmp'],
)
tools = await load_mcp_tools(session=None, connection=conn)
t = tools[0]  # e.g., 'read_file'

print(f"t.func = {t.func}")       # None
print(f"t.coroutine = {t.coroutine}")  # Not None

# This works (async)
result = await t.ainvoke({'path': '/tmp/test.txt'})

# This fails (sync)
result = t.invoke({'path': '/tmp/test.txt'})
# Raises: NotImplementedError: StructuredTool does not support sync invocation.