fix: parse MCP result payloads and drop place idempotency_key

Typed result structs replace empty envelopes. Equity place sends
ref_id only so live additionalProperties:false schemas accept the call.

options/write.go

@@ -57,11 +57,18 @@ type ReplaceOrderRequest struct {
 }
 
 // ReviewResult is the pre-trade check from review_option_order.
-type ReviewResult struct{}
+type ReviewResult struct {
+	Errors   []string `json:"errors"`
+	Warnings []string `json:"warnings"`
+	Alerts   []string `json:"alerts"`
+}
 
-// Order is a placed or replaced option order.
+// Order is a placed, replaced, or listed option order.
 type Order struct {
-	ID string `json:"id"`
+	ID    string          `json:"id"`
+	State string          `json:"state"`
+	Qty   decimal.Decimal `json:"-"`
+	Price decimal.Decimal `json:"-"`
 }
 
 // CancelOrderRequest is the argument set for cancel_option_order.
@@ -81,7 +88,10 @@ type ExerciseRequest struct {
 }
 
 // ExerciseResult is the parsed exercise_option payload.
-type ExerciseResult struct{}
+type ExerciseResult struct {
+	ID    string `json:"id"`
+	State string `json:"state"`
+}
 
 // CancelExerciseRequest is the argument set for cancel_option_exercise.
 type CancelExerciseRequest struct {
@@ -100,11 +110,18 @@ func (c *Client) ReviewOrder(ctx context.Context, req PlaceOrderRequest) (Review
 
 // PlaceOrder calls place_option_order. RefID is sent as ref_id.
 func (c *Client) PlaceOrder(ctx context.Context, req PlaceOrderRequest) (Order, error) {
-	var out Order
-	if err := c.parse(ctx, toolPlace, placeArgs(req, true, false), &out); err != nil {
+	raw, err := c.c.Call(ctx, toolPlace, placeArgs(req, true, false))
+	if err != nil {
 		return Order{}, err
 	}
-	return out, nil
+	ords, err := parseOrders(raw)
+	if err != nil {
+		return Order{}, client.ToolErrorf(toolPlace, "parse: %w", err)
+	}
+	if len(ords) > 0 {
+		return ords[0], nil
+	}
+	return Order{}, nil
 }
 
 // CancelOrder calls cancel_option_order.
@@ -137,11 +154,18 @@ func (c *Client) ReplaceOrder(ctx context.Context, req ReplaceOrderRequest) (Ord
 	if req.OrderID != "" {
 		args["order_id"] = req.OrderID
 	}
-	var out Order
-	if err := c.parse(ctx, toolReplace, args, &out); err != nil {
+	raw, err := c.c.Call(ctx, toolReplace, args)
+	if err != nil {
 		return Order{}, err
 	}
-	return out, nil
+	ords, err := parseOrders(raw)
+	if err != nil {
+		return Order{}, client.ToolErrorf(toolReplace, "parse: %w", err)
+	}
+	if len(ords) > 0 {
+		return ords[0], nil
+	}
+	return Order{}, nil
 }
 
 // Exercise calls exercise_option.