Compare Agent Versions
compare_agent_versionsTwo versions of ONE agent side by side over the same window — traces, failed rate, cost per trace, latency p50, TTFT p50 and tokens per trace — with the change between them, so "did v8 make it worse" is one call.
It is agent_traces_summary twice, each scoped through the registry filter for one version, and the same six rows and delta rules as the Rius console's compare tiles, so an agent and a human read one change. The change is in percentage points for the failed rate ("+1.0 pp", never "+50%") and a percent of the base otherwise; a dash means a side is unknown or the base is zero, never "no change". Below 20 traces on either side the reply says the differences can be noise; it never claims significance either way.
Refuses, rather than answering, where this deployment's filter registry does not advertise the version field: an older core would ignore the filter and return the whole agent's numbers on both sides, which would read as a confident "no change".
agent: the exact agent name (required). Read it off list_agents or off
root_agent on list_agent_traces.
dimension: which version identity to compare — agent (the agent
definition, rius.main_agent.version) or service (the build,
service.version; build is accepted as a synonym). The two are not
interchangeable: read the values off agent_versions, which labels each.
base: the older version's exact value, as agent_versions lists it.
head: the newer version's exact value; the change is head against base.
workspace: optional workspace id, name, or org-name/workspace-name when
the same name occurs in two of your orgs (defaults to your default;
use list_workspaces to discover them).
hours: lookback window in hours (default 24), used for whichever of start/end
is not given.
start: optional absolute RFC3339 lower bound (e.g. "2026-08-01T00:00:00Z");
overrides the hours-derived value when given.
end: optional absolute RFC3339 upper bound; overrides the hours-derived value
when given.
instance: optional exact instance id, narrowing both sides to one running copy
of agent.
Example:
Did planner's version 8 make things worse than 7 this week?
{
"name": "compare_agent_versions",
"arguments": {
"agent": "planner", "dimension": "agent", "base": "7", "head": "8",
"hours": 168
}
}Compare the last two builds of planner.
{
"name": "compare_agent_versions",
"arguments": {
"agent": "planner", "dimension": "service", "base": "2.3.1", "head": "2.4.0"
}
}Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| end | No | ||
| base | Yes | ||
| head | Yes | ||
| agent | Yes | ||
| hours | No | ||
| start | No | ||
| instance | No | ||
| dimension | Yes | ||
| workspace | No |
Output Schema
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |