Require API key and handle server errors

[qrpike]

Summary

• enforce POLYGON_API_KEY in server and entrypoint
• add basic error handling and cleanup in run
• document failure when API key is missing

Testing

• python -m py_compile entrypoint.py src/mcp_polygon/server.py

[qrpike]

If the env variable is required to function, we should error if it's not set.

[Copilot]

Pull Request Overview

This PR ensures the POLYGON_API_KEY must be set before startup, adds basic error handling and resource cleanup in the server’s run function, and updates documentation to reflect the failure mode when the key is missing.

• Enforce POLYGON_API_KEY presence and raise an error if it’s not set in both server.py and entrypoint.py.
• Wrap the server launch in a try/except/finally to log errors and close the REST client.
• Update README to note that the server will exit if the API key isn’t configured.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
src/mcp_polygon/server.py	Enforce API key, add try/except/finally around run, clean up client
entrypoint.py	Enforce API key check on startup
README.md	Document server exit behavior when API key is missing

Comments suppressed due to low confidence (2)

src/mcp_polygon/server.py:11

• Add a unit test for server initialization to ensure it raises an EnvironmentError when POLYGON_API_KEY is not set.

raise EnvironmentError("POLYGON_API_KEY environment variable not set.")

entrypoint.py:9

• Consider adding a test to verify that start_server() exits with an EnvironmentError when POLYGON_API_KEY is missing.

raise EnvironmentError("POLYGON_API_KEY environment variable not set.")

[Copilot]

Catching a broad Exception may mask unexpected errors; consider catching more specific exceptions or allowing critical errors to propagate.

Suggested change

	except Exception as exc:
	print(f"Error running Polygon MCP server: {exc}")
	raise
	finally:
	try:
	polygon_client.close()
	except Exception as close_exc:
	print(f"Error closing Polygon REST client: {close_exc}")
	except RuntimeError as exc:
	print(f"Runtime error while running Polygon MCP server: {exc}")
	raise
	except ValueError as exc:
	print(f"Value error while running Polygon MCP server: {exc}")
	raise
	finally:
	try:
	polygon_client.close()
	except OSError as close_exc:
	print(f"OS error while closing Polygon REST client: {close_exc}")

[Copilot]

Prefer using a logging framework instead of print statements for error reporting to ensure consistent log management and easier debugging.

Suggested change

	print(f"Error running Polygon MCP server: {exc}")
	raise
	finally:
	try:
	polygon_client.close()
	except Exception as close_exc:
	print(f"Error closing Polygon REST client: {close_exc}")
	logging.error(f"Error running Polygon MCP server: {exc}")
	raise
	finally:
	try:
	polygon_client.close()
	except Exception as close_exc:
	logging.error(f"Error closing Polygon REST client: {close_exc}")

[Copilot]

[nitpick] Retrieval and validation of POLYGON_API_KEY is duplicated in server.py; consider centralizing this logic in a shared helper function.