Captures the current browser page as a PNG, so you can verify what the browser is displaying without relying on a full-screen capture.
截取当前页面（不是整屏）。返回 PNG。 页面级截图比全屏截图更适合判断"浏览器里现在是什么状态"。
| Name | Required | Description | Default |
|---|---|---|---|
| session | No | 会话 id，省略则用当前会话 |
Changes observed during successful MCP inspections.
v0.2.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description does carry the burden of behavioral disclosure. It usefully states that the result is a PNG and that the capture is page-level rather than full-screen, but it does not mention prerequisites such as an open browser/CDP target, read-only/safety behavior, or failure cases.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is short, front-loaded, and every sentence adds useful information: scope, return format, and rationale for choosing page-level screenshots.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple one-parameter screenshot tool with no output schema and no annotations, the description covers the key behavioral facts: current page only, PNG output, and when it is more useful than full-screen capture. It could be more complete by noting browser/CDP prerequisites, but the essentials are present.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the optional session parameter is already documented in the input schema. The description does not add any parameter-level semantics beyond the schema; a baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb and resource: capture the current page, explicitly not the full screen, and returns PNG. It also distinguishes the tool's scope from full-screen screenshots, which is a sibling capability (desktop_screenshot).
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It gives clear usage context: use page-level screenshots when the goal is to judge the browser page state, compared with full-screen screenshots. It does not explicitly name the alternative sibling tool or state when not to use this tool, so it stops short of full when/when-not guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.