Document browser reliability layer and roadmap progress

docs/api/PROTOCOL.md

@@ -1302,6 +1302,10 @@ Set callback for tool use events (for confirmation UI).
 
 List available tools.
 
+When browser automation is enabled, `tools.list` may include workflow-reliability helpers such as:
+`browser.wait_for`, `browser.assert`, `browser.extract`, `browser.checkpoint.save`, and `browser.checkpoint.resume`
+in addition to baseline navigation/click/type/content/eval tools.
+
 **Request:**
 ```json
 {
@@ -1338,6 +1342,9 @@ List available tools.
 
 Execute a tool directly (bypass agent).
 
+Browser workflow tools enforce runtime guardrails configured in `browser.*`:
+domain allowlists, high-risk-domain confirmation (`confirm_high_risk=true`), retry bounds, and step-budget limits.
+
 **Request:**
 ```json
 {