Captures a PNG screenshot of the target browser tab, optionally including the full page. Use it when a visual capture is needed; prefer page snapshots or text for locating elements.
PNG screenshot of the target tab. Use sparingly — prefer snapshot or text for locating elements.
| Name | Required | Description | Default |
|---|---|---|---|
| fullPage | No |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden: 'use sparingly' hints at cost but never quantifies it, and it doesn't say whether the capture is of the viewport by default, whether it includes chrome/overlays, or what permissions are needed. The scoping to 'the target tab' is the one useful behavioral fact added.
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?
Two short sentences, zero filler, with the core capability front-loaded and the usage caution second.
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?
A screenshot tool is conceptually simple and the return type is self-evident from 'PNG screenshot', so no output schema is needed. But the sole parameter is undocumented and the cost/permission profile is only hinted at, leaving real gaps for a no-annotation tool.
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 coverage is 0% for the single fullPage boolean and the description never mentions it, so an agent gets no guidance on what turning fullPage on actually changes or when to use it. This is exactly the case where the description should compensate and doesn't.
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?
States the concrete output (PNG screenshot) and target (the target tab), which immediately distinguishes it from text-oriented siblings. It does not spell out a verb but 'screenshot' plus 'target tab' is unambiguous.
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?
Explicitly warns to use it sparingly and names two alternatives (snapshot, text) plus the condition that selects them (locating elements). It stops short of saying when a screenshot IS the right choice, such as visual layout verification.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.