diff --git a/agent/turn.go b/agent/turn.go
index 8ecdd15..b51268d 100644
--- a/agent/turn.go
+++ b/agent/turn.go
@@ -132,6 +132,18 @@ func (ag *Agent) executeTurn(ctx context.Context, input string) string {
 		return ""
 	}
 	tools := toolInfosToBackend(ti)
+
+	// Build output format lookup from the fresh tool list. This ensures
+	// dynamically loaded tools (via tool_load) have their outputFormat
+	// available immediately, not just after a full runtime rebuild.
+	outputFormats := make(map[string]string, len(ti))
+	for _, info := range ti {
+		outputFormats[info.Name] = info.OutputFormat
+	}
+	outputFormatFn := func(name string) string {
+		return outputFormats[name]
+	}
+
 	ag.cfg = agentConfig{
 		Backend:          ag.runtime.Backend,
 		preamble:         ag.runtime.Preamble,
@@ -139,7 +151,7 @@ func (ag *Agent) executeTurn(ctx context.Context, input string) string {
 		Tools:            tools,
 		Exec:             ag.runtime.Exec,
 		ClassifyTool:     ag.runtime.ClassifyTool,
-		OutputFormat:     ag.runtime.OutputFormat,
+		OutputFormat:     outputFormatFn,
 		ClassifyTier:     ag.runtime.ClassifyTier,
 		GenerationParams: ag.runtime.GenParams,
 		MaxSteps:         ag.runtime.MaxSteps,