fix(anthropic): prevent NOT_GIVEN sentinel leak in tools event guard

[cschanhniem]

Fixes #4230

The tools guard in emit_input_events() used is not None which lets the Anthropic SDK's NOT_GIVEN sentinel through when tools is omitted. NOT_GIVEN satisfies is not None, causing it to be placed in the MessageEvent body as {"tools": NOT_GIVEN}. The OTLP log exporter then fails to encode the unrepresentable type with:

Exception: Invalid type <class 'anthropic.NotGiven'> of value NOT_GIVEN

This drops the entire log batch and produces recurring traceback noise.

The system branch immediately above uses a truthiness check which correctly drops NOT_GIVEN (bool(NOT_GIVEN) is False). This fix aligns the tools guard with that pattern. NOT_GIVEN and empty lists are both falsy, so the event is correctly skipped in both cases.

Change: if kwargs.get("tools") is not None: → if kwargs.get("tools"):

Summary by CodeRabbit

• Bug Fixes
  • Corrected telemetry event emission behavior to properly handle empty tools values during instrumentation tracking.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b96af403-1609-4ae2-8e78-05d8fe9615c2

📥 Commits

Reviewing files that changed from the base of the PR and between fc33f1c and 46b544c.

📒 Files selected for processing (1)

• packages/opentelemetry-instrumentation-anthropic/opentelemetry/instrumentation/anthropic/event_emitter.py

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📝 Walkthrough

Walkthrough

In event_emitter.py, the guard condition for emitting a tools-as-user-message event in emit_input_events is changed from kwargs.get("tools") is not None to if kwargs.get("tools"), aligning it with the existing truthiness check used for the system branch.

Changes

Fix NOT_GIVEN sentinel leak in tools event emission

Layer / File(s)	Summary
Truthiness guard for tools in emit_input_events packages/opentelemetry-instrumentation-anthropic/opentelemetry/instrumentation/anthropic/event_emitter.py	Replaces kwargs.get("tools") is not None with if kwargs.get("tools") so that falsy values — including the Anthropic SDK NOT_GIVEN sentinel and empty lists — no longer cause a MessageEvent with an unserializable body to be emitted.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Poem

A single is not None slipped past the gate,
Letting NOT_GIVEN crash the export crate.
🐇 One truthiness check, neat and lean,
Keeps the sentinel hidden, unseen.
Now logs flow out, tidy and great!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and concisely describes the main change: replacing a non-None check with a truthiness check to prevent the NOT_GIVEN sentinel from leaking into tools events.
Linked Issues check	✅ Passed	The code change directly addresses all four objectives: prevents sentinel leakage via truthiness check, aligns tools with system parameter's existing pattern, ensures omitted tools are not emitted, and restores reliable OTLP log export.
Out of Scope Changes check	✅ Passed	The change is narrowly scoped to the single-line fix in emit_input_events() that was documented in the linked issue, with no extraneous modifications.

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✨ Finishing Touches

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[cschanhniem]

Just saw the CLA check — will sign the CLA now so this can move forward.