Capture a screenshot of the currently running game. Returns the game canvas content as a base64-encoded image (PNG or JPEG). Supports all game types: plain Canvas2D, WebGL (Unity, Cocos, Three.js, etc.). The game MUST be running (call run_game first if not). Use this to visually inspect the curre...
Part of the Weixin Minigame Helper server.
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AI agents call capture_screenshot to retrieve information from Weixin Minigame Helper without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though capture_screenshot only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"capture_screenshot": {}
}
}See the full Weixin Minigame Helper policy for all 6 tools.
These attack patterns abuse exactly the kind of access capture_screenshot gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Capture a screenshot of the currently running game. Returns the game canvas content as a base64-encoded image (PNG or JPEG). Supports all game types: plain Canvas2D, WebGL (Unity, Cocos, Three.js, etc.). The game MUST be running (call run_game first if not). Use this to visually inspect the current game state, verify rendering output, debug visual issues, or confirm that UI changes look correct.. It is categorised as a Read tool in the Weixin Minigame Helper MCP Server, which means it retrieves data without modifying state.
Register the Weixin Minigame Helper MCP server in PolicyLayer and add a rule for capture_screenshot: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Weixin Minigame Helper. Nothing to install.
capture_screenshot is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the capture_screenshot rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for capture_screenshot. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
capture_screenshot is provided by the Weixin Minigame Helper MCP server (@weadmin/weixin-minigame-helper-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 6 Weixin Minigame Helper tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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