[DOCS] Monitoring usage docs missing OTel `speed` attribute and trace span guidance for fast mode

Documentation Type

Missing documentation (feature not documented)

Documentation Location

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

Section/Topic

"Available metrics and events" (Standard attributes and event attribute lists), plus coverage for trace span attributes.

Current Documentation

The page currently lists shared attributes as:

session.id, app.version, organization.id, user.account_uuid, terminal.type

And the API request event attributes as:

model, cost_usd, duration_ms, input_tokens, output_tokens, cache_read_tokens, cache_creation_tokens

There is no documented speed attribute and no trace span attribute reference on this page.

What's Wrong or Missing?

Claude Code changelog 2.1.39 says:

Added speed attribute to OTel events and trace spans for fast mode visibility

But monitoring-usage does not document:

• The new speed field for OpenTelemetry event payloads.
• Where speed appears in trace spans.
• Expected values (for example, standard vs fast) and how to use them for filtering.

Without this, users cannot reliably segment fast-mode vs standard traffic in their OTel backend using the docs alone.

Suggested Improvement

1. Add speed to the OTel attribute documentation in monitoring-usage.
2. Document expected values and semantics (for example, standard and fast, if those are the canonical values).
3. Add a short "Trace spans" subsection describing where speed is emitted for traces.
4. Add one concrete query/filter example showing fast-mode visibility (for example, filter by speed = "fast").

Impact

Medium - Makes feature difficult to understand

Additional Context

Affected Pages:

| Page | Context |
|------|---------|
| https://code.claude.com/docs/en/monitoring-usage | OTel schema reference is missing speed and trace-span visibility notes |
| https://code.claude.com/docs/en/fast-mode | Fast mode is documented, but monitoring linkage via OTel speed is not surfaced |

Total scope: 2 pages affected

Source: Claude Code changelog 2.1.39

Entry: "Added speed attribute to OTel events and trace spans for fast mode visibility"