🐛 Bug Report: Missing warning message when no instrumentors are initialized

[ronensc]

Which component is this bug for?

Traceloop SDK

📜 Description

When no instrumentors are initialized via Traceloop.init(), no warning message is emitted.
This makes it harder to detect misconfiguration or missing dependencies.

👟 Reproduction steps

1. Create a fresh virtual environment.

2. Install the SDK (and no other LLM/framework package):

pip install traceloop-sdk==0.40.12  

3. Run the following code:

from traceloop.sdk import Traceloop
from traceloop.sdk.instruments import Instruments

Traceloop.init(instruments={Instruments.MCP})

4. Observe that no warning is printed, even though no instrumentors are active.

👍 Expected behavior

A warning message should be emitted when no instrumentors are initialized, e.g.:

Warning: No valid instruments set. 

👎 Actual Behavior with Screenshots

none

🤖 Python Version

No response

📃 Provide any additional context for the Bug.

It appears that the issue stems from the init_<x>_instrumentor() functions returning True even when no instrumentation actually occurs — for example, when the corresponding package is not installed.

Here’s an example from init_mcp_instrumentor():

openllmetry/packages/traceloop-sdk/traceloop/sdk/tracing/tracing.py

Lines 1039 to 1054 in 20a4e4b

	def init_mcp_instrumentor():
	try:
	if is_package_installed("mcp"):
	Telemetry().capture("instrumentation:mcp:init")
	from opentelemetry.instrumentation.mcp import McpInstrumentor
	instrumentor = McpInstrumentor(
	exception_logger=lambda e: Telemetry().log_exception(e),
	)
	if not instrumentor.is_instrumented_by_opentelemetry:
	instrumentor.instrument()
	return True
	except Exception as e:
	logging.error(f"Error initializing MCP instrumentor: {e}")
	Telemetry().log_exception(e)
	return False

There's an easy fix to apply to all instrumentors - move the return True statement inside the if is_package_installed() block to avoid false positives:

def init_mcp_instrumentor():
    try:
        if is_package_installed("mcp"):
            Telemetry().capture("instrumentation:mcp:init")
            from opentelemetry.instrumentation.mcp import McpInstrumentor

            instrumentor = McpInstrumentor(
                exception_logger=lambda e: Telemetry().log_exception(e),
            )
            if not instrumentor.is_instrumented_by_opentelemetry:
                instrumentor.instrument()
            return True
    except Exception as e:
        logging.error(f"Error initializing MCP instrumentor: {e}")
        Telemetry().log_exception(e)
    return False

This pattern should be applied to all instrumentor init functions.

👀 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?

Yes I am willing to submit a PR!