🐛 Bug Report: MCP Python instrumentation failed to parse HTTP Status code

[thisthat]

Which component is this bug for?

AlephAlpha Instrumentation

📜 Description

In the case that a tool call has an error, the instrumentation tries to attach an error code to the span

openllmetry/packages/opentelemetry-instrumentation-mcp/opentelemetry/instrumentation/mcp/instrumentation.py

Lines 297 to 302 in 5bd93d9

	if hasattr(result, "isError") and result.isError:
	if len(result.content) > 0:
	span.set_status(Status(StatusCode.ERROR, f"{result.content[0].text}"))
	error_type = get_error_type(result.content[0].text)
	if error_type is not None:
	span.set_attribute(ERROR_TYPE, error_type)

The error code is derived by looking into the error message for any number and convert it to HTTPStatus

openllmetry/packages/opentelemetry-instrumentation-mcp/opentelemetry/instrumentation/mcp/instrumentation.py

Lines 401 to 408 in 5bd93d9

	def get_error_type(error_message):
	if not isinstance(error_message, str):
	return None
	match = re.search(r"\b(4\d{2}|5\d{2})\b", error_message)
	if match:
	num = int(match.group())
	if 400 <= num <= 599:
	return HTTPStatus(num).name

However, the HTTPStatus enum has a well-defined list of possible values (see them here). If the error message contains a random number, say, a port number like HTTPS 443, the HTTPStatus class will throw an error with the message 443 is not a valid HTTPStatus.

👟 Reproduction steps

Set up an MCP server where a tool call returns an error containing a number that is not part of the HTTPStatus enum.

👍 Expected behavior

The span should configure the error.type to be something like MCP tool Error. Parsing the first number found in the message as an HTTP status code is flaky and not representative of the error. If a network error occurs, the HTTP Instrumentation will report it.

👎 Actual Behavior with Screenshots

The tool call span wrongly reports the error as the HTTPStatus parsing error instead of the tool error.

🤖 Python Version

No response

📃 Provide any additional context for the Bug.

No response

👀 Have you spent some time to check if this bug has been raised before?

• I checked and didn't find similar issue

Are you willing to submit PR?

None

[nirga]

Thanks @thisthat you're right! Not sure who implemented this weird behavior