Fix: Skip currently executing file during tool discovery

[EricGustin]

The Bug:

When an entrypoint file imports its parent package and calls add_tools_from_module() on that package, and the same entrypoint file also defines tools using @app.tool or @tool decorators, then the server fails to start with an AttributeError. This is because the tools would be discovered via AST parsing, but those tools weren't added to the module's namespace yet because the file is still executing.

For example, this would fail on startup:

#!/usr/bin/env python3
"""local_filesystem MCP server"""

import sys
from typing import Annotated

from arcade_mcp_server import MCPApp

import local_filesystem

app = MCPApp(name="eric_server", version="1.0.0", log_level="DEBUG")


app.add_tools_from_module(local_filesystem)


@app.tool
def eric(name: Annotated[str, "The name of the person to greet"]) -> str:
    """Greet a person by name."""
    return "return"


if __name__ == "__main__":
    transport = sys.argv[1] if len(sys.argv) > 1 else "stdio"

    app.run(transport="http", host="127.0.0.1", port=8074)

The fix:

Skip the entrypoint file. This means that any tool defined inside of the entrypoint file must be added via MCPApp.add_tool(...) or instead use the recommended @app.tool.

[codecov]

Codecov Report

❌ Patch coverage is 14.28571% with 12 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
libs/arcade-core/arcade_core/toolkit.py	14.28%	12 Missing ⚠️

📢 Thoughts on this report? Let us know!

[EricGustin]

Codecov Report

❌ Patch coverage is 14.28571% with 12 lines in your changes missing coverage. Please review.

Files with missing lines Patch % Lines
libs/arcade-core/arcade_core/toolkit.py 14.28% 12 Missing ⚠️
📢 Thoughts on this report? Let us know!

These changes are fully covered by the E2E integration test now which aren't included in the codecov report