Tool pairs

Which tools get called alongside each other inside a session, and what a strong pair usually means.

Tool pairs count consecutive calls within a session: how often to_tool was called immediately after from_tool.

The panel sits last on the overview, under the tool table. It reads as a footnote to that table, and it is the one panel that can be absent entirely — so nothing below it moves when it is.

How it is computed

By the nightly pass, walking each session’s calls in started_at order and recording each adjacent pair. Stored per day and per client, so it aggregates across any range and narrows to one model.

Like retries and first-call success, it lags by one day and is labelled as of yesterday.

What a strong pair usually means

Direction matters, and so does whether the pair is symmetric.

Pattern	Usual reading
search_x → get_x	Healthy. Find then fetch is the shape most servers want.
get_x → get_x	Not shown here — a tool following itself within 30 seconds is a retry, and belongs to that metric.
a → b almost always	The two are one operation. Consider merging them, or having a return what b fetches.
b → a and a → b equally	The model is bouncing. Usually neither tool’s result says what to do next.

The most actionable pattern is the third. A pair that fires on nearly every session is two round trips and two sets of schema bytes doing the work of one — and each hop is another chance for the model to get it wrong.

Under a tool filter

Pairs are filtered to those that touch a selected tool. A pair between two tools you excluded is not part of what you asked to see.

Up to eight pairs are shown on the overview, and up to ten on a tool page, where they are scoped to pairs involving that tool.

When there is nothing here

Three reasons, all normal:

• The nightly pass has not covered any day in the range yet.
• Sessions hold one call each, so there are no adjacent pairs.
• Sessions are fragmenting — see Serving over HTTP.

Related

• Sessions
• First-call success