fix(tools): clarify chart data format

.opencode/tools/show_chart.ts

@@ -1,7 +1,8 @@
 import { tool } from "@opencode-ai/plugin";
 
 export default tool({
-  description: "在前端对话界面中渲染图表。",
+  description:
+    "在前端对话界面中渲染图表。折线图/柱状图必须使用 x_data 作为横轴标签，series[].data 作为同长度的一维数值数组，不要把折线数据写成 ECharts 的 [x, y] 二维点数组。",
   args: {
     reason: tool.schema
       .string()
@@ -11,12 +12,16 @@ export default tool({
       .enum(["line", "bar", "pie"])
       .optional()
       .describe("Chart type."),
-    x_data: tool.schema.array(tool.schema.string()).describe("X-axis labels."),
+    x_data: tool.schema
+      .array(tool.schema.string())
+      .describe("X-axis labels. For line charts, put time/category labels here."),
     series: tool.schema
       .array(
         tool.schema.object({
           name: tool.schema.string(),
-          data: tool.schema.array(tool.schema.number()),
+          data: tool.schema
+            .array(tool.schema.number())
+            .describe("Y values only. Must align by index with x_data."),
           type: tool.schema.enum(["line", "bar"]).optional(),
         }),
       )