Update evals docs: Add tool-usage argument matching feature

build/agents/build-your-agent/evals.mdx

@@ -1,18 +1,18 @@
 ---
 title: 'Evals'
 sidebarTitle: 'Evals'
 description: 'Test and evaluate your AI Agents with scenario-based evaluations and reusable Checks'
 ---
 
 <Info>
 **Rollout Status**: Evals is rolling out progressively, starting with Enterprise customers. If you don't see this feature in your account yet, reach out to your account manager to discuss access.
 </Info>
 
 The Evals section is your command center for testing and evaluating AI Agent performance. Located in the **Evaluate** tab (next to the Build and Use tabs) in the Agent builder, Evals lets you create test sets, define reusable Checks, run automated evaluations, and monitor live Agent quality — all without manual testing.
 
 ![Evaluate tab showing the Evals sidebar (Test, Runs, Checks, Publish, Monitor) and a Monitor dashboard with overall score, total runs, and Checks breakdown](/images/agent/agent-evals.png)
 
 ## What you can do with Evals
 
 <CardGroup cols={3}>
   <Card title="Run tests" icon="flask-vial">
@@ -28,11 +28,11 @@
 
 ---
 
 ## Evals sections
 
 The Evals area has five sections, shown in the left sidebar of the Evaluate tab:
 
 - **Test** — Create and manage test sets. Each test set holds scenarios that simulate users; running a scenario produces a conversation with your Agent that gets scored by attached Checks.
 - **Runs** — Past evaluation run results. Browse average scores, tasks evaluated, progress status, credit spend, and creation date for every run.
 - **Checks** — The reusable set of evaluation criteria. Create a Check once, then attach it to scenarios, to Monitor dashboards, or to one-off evaluations of completed tasks.
 - **Publish** — Choose which test sets must pass before your Agent can be published. Set a minimum pass rate and optionally block publishing on failure.
@@ -89,6 +89,23 @@
     | **Tool** | Select the tool to check for |
     | **Position** | Whether the tool was used anywhere, used first, or used last |
     | **Comparison** | Check if the tool was used at least, exactly, or at most X times |
+
+    #### Argument conditions
+
+    You can add conditions to verify the specific arguments passed to tool calls, not just whether the tool was called. Each condition specifies an argument path and a match type, and all conditions must be satisfied for the check to pass.
+
+    | Match type | Description |
+    |------------|-------------|
+    | **Exact match** | The argument value must equal the specified value. Optionally enable case-insensitive matching to ignore capitalization. |
+    | **Contains** | The argument value must include the specified substring. |
+    | **Regex** | The argument value must match the specified regular expression pattern. |
+    | **Not empty** | The argument must have any non-empty value. |
+
+    To add conditions, click **+ Add condition** in the **Conditions** section of the eval rule form. For each condition, specify the argument path and the value or pattern to match against. A plain-English preview of your conditions appears in the form.
+
+    <Info>
+    Argument conditions work for both single-agent evals and workforce (node-scoped) evals. This feature is currently behind the `evals-toolusage-argument-matcher` feature flag.
+    </Info>
   </Accordion>
 </AccordionGroup>
 
@@ -284,7 +301,7 @@
 
 You also get:
 
 - **Overall score timeseries** to spot regressions or improvements over time.
 - **Per-Check charts** so you can see which criteria are slipping.
 - **Version markers** that line up score changes with Agent publishes.
 - **A list of evaluation runs** with score, name, and a drill-in to the full conversation.