Pencil MCP Get Screenshot

Tools

This skill is designed to call the Pencil MCP tool:

• get_screenshot

If your client namespaces MCP tools, it may appear as mcp__pencil__get_screenshot.

When to use this skill

Intent Recognition (CRITICAL)

Even if a trigger phrase matches, you must verify the user's intent:

1. Is the user explicitly asking to use "Pencil"?
2. Is the current conversation context clearly about "Pencil" design tasks?

If the answer is NO, do NOT use this skill. (e.g., "Get screenshot" might refer to a browser screenshot via Puppeteer).

CRITICAL PREREQUISITE: You must ONLY use this skill when the user EXPLICITLY mentions "Pencil".

ALWAYS use this skill when:

• You have completed a design operation (batch_design) and need to verify the result in Pencil.
• The user asks to "Show me" or "Take a look" at the Pencil design.
• You need to check for visual bugs (text overflow, alignment, contrast).
• This is the Verify step in the Design Loop.

Trigger phrases include:

• "Get Pencil screenshot" (获取 Pencil 截图)
• "Pencil visual check" (Pencil 视觉检查)
• "Verify Pencil design" (验证 Pencil 设计)
• "Show me the button in Pencil" (给我看 Pencil 里的那个按钮)

Input Parameters

• filePath (string, optional): Path to access a specific .pen file.
• nodeId (string, required): The ID of the node to screenshot.

How to use this skill

1. Identify Target: Get the nodeId of the element you just modified or created.
2. Call Tool: get_screenshot(nodeId='...').
3. Analyze Result:
   • The tool returns an image URL or data.
   • CRITICAL: You must "look" at the image (if capabilities allow) or present it to the user for feedback.
   • Check for: Alignment, Spacing, Text Truncation, Color correctness.

Examples

1. Simple: Node Screenshot

Get a visual verification of a single element. See 1-node-screenshot.json.

2. Medium: Frame Verification

Screenshot a whole frame to check layout and composition. See 2-frame-verification.json.

3. Complex: Design System Check

Screenshot a component master to ensure the design system update looks correct. See 3-component-check.json.

Keywords

English keywords: get screenshot, visual verification, check design, view node, render image, visual audit

Chinese keywords (中文关键词): 获取截图, 视觉验证, 检查设计, 查看节点, 渲染图片, 视觉审计

能力边界

✅ 适用场景

• 当你需要使用此技能对应的技术栈时
• 当项目需要遵循最佳实践时
• 当需要快速上手或深入理解核心概念时

⚠️ 需要注意

• 复杂业务逻辑需要结合具体场景调整
• 性能优化需要根据实际数据量评估

❌ 不适用场景

• 不相关的技术栈或框架
• 需要完全自定义的特殊场景

常见陷阱 (Gotchas)

1. 版本兼容性：注意框架版本与依赖库的兼容性，不同版本 API 可能有差异
2. 配置文件格式：配置文件格式错误是最常见的问题，建议使用编辑器的语法检查
3. 环境变量：确保所有必要的环境变量已正确设置，敏感信息不要硬编码
4. 依赖冲突：多版本共存时注意依赖冲突，使用 lock 文件锁定版本
5. 性能陷阱：大数据量场景下注意性能优化，避免 N+1 查询等常见问题

使用流程

Step 1: 环境准备

确保开发环境已安装必要的依赖和工具。

Step 2: 配置初始化

根据项目需求进行基础配置。

Step 3: 核心功能使用

按照示例代码实现核心功能。

Step 4: 测试验证

运行测试确保功能正常。

Step 5: 部署上线

完成开发后进行部署和监控。