[DOCS] Monitoring reference missing new OpenTelemetry tool event attributes

Documentation Type

Incorrect/outdated documentation

Documentation Location

https://code.claude.com/docs/en/monitoring-usage

Section/Topic

Events → claude_code.tool_result and claude_code.tool_decision

Current Documentation

The docs currently list these attributes for the two tool-related OpenTelemetry events:

Event Name: claude_code.tool_result event.name: "tool_result" tool_name: Name of the tool success: "true" or "false" duration_ms: Execution time in milliseconds error: Error message (if failed) decision_type: Either "accept" or "reject" decision_source: Decision source - "config", "hook", "user_permanent", "user_temporary", "user_abort", or "user_reject" tool_result_size_bytes: Size of the tool result in bytes

and:

Event Name: claude_code.tool_decision event.name: "tool_decision" tool_name: Name of the tool (for example, "Read", "Edit", "Write", "NotebookEdit") decision: Either "accept" or "reject" source: Decision source - "config", "hook", "user_permanent", "user_temporary", "user_abort", or "user_reject"

I could not find any mention on this page of tool_use_id for either event or tool_input_size_bytes for tool_result.

What's Wrong or Missing?

Changelog v2.1.119 says:

OpenTelemetry: tool_result and tool_decision events now include tool_use_id; tool_result also includes tool_input_size_bytes

But the monitoring reference still shows the older event schemas.

That leaves the canonical OpenTelemetry event documentation outdated in two ways:

A. Missing tool_use_id on both tool events

Users reading the docs will not know that claude_code.tool_result and claude_code.tool_decision can now be correlated to a specific tool invocation with tool_use_id.

B. Missing tool_input_size_bytes on tool_result

Users reading the docs will not know that claude_code.tool_result now also exposes tool input size in bytes, alongside the already-documented tool_result_size_bytes.

Suggested Improvement

Update the attribute lists in the Monitoring reference for both events:

• Add tool_use_id to claude_code.tool_result
• Add tool_use_id to claude_code.tool_decision
• Add tool_input_size_bytes to claude_code.tool_result

It would also help to briefly describe what each new field is used for:

• tool_use_id: identifier that lets users join decision/result events back to the same tool invocation
• tool_input_size_bytes: size of the tool input payload in bytes

If there are any conditions on when these attributes are emitted, document those conditions in the same section.

Impact

Medium - Makes feature difficult to understand

Additional Context

Affected Pages:

| Page | Context |
|------|---------|
| https://code.claude.com/docs/en/monitoring-usage | Canonical OpenTelemetry reference for Claude Code event names and attributes |
| https://code.claude.com/docs/en/agent-sdk/observability | Sends Agent SDK users to the Monitoring reference for the complete list of event names and attributes |

Total scope: 2 pages affected

Source: Changelog v2.1.119

Exact changelog entry:

OpenTelemetry: tool_result and tool_decision events now include tool_use_id; tool_result also includes tool_input_size_bytes