Capture a PNG screenshot of the active browser tab or native window and return it to the assistant. Native windows require Screen Recording permission.
Return a PNG of the controlled browser tab or native window to the calling assistant. Native capture requires Screen Recording permission.
| Name | Required | Description | Default |
|---|---|---|---|
| sessionId | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=true and destructiveHint=false, which the description does not contradict. The description adds value by disclosing the permission requirement for native capture, which is a behavioral prerequisite not covered by annotations. It does not, however, explain any side effects, error behaviors, or limitations beyond permission.
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 a single, front-loaded sentence that immediately states the output and target, followed by a necessary permission note. Every word adds value, with no redundancy or filler.
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?
The tool is simple, with one parameter and no output schema. The description explains the return type (PNG) and the capture source. However, the lack of any parameter explanation leaves a gap in completeness, as the agent cannot determine what sessionId refers to without additional context. The permission note adds operational context but does not cover parameter semantics.
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?
The sole parameter sessionId is not described in the input schema (0% coverage) and the description does not mention it at all. The phrase 'controlled browser tab or native window' implies a session context, but the description fails to explicitly link sessionId to identifying the target session. This leaves the parameter's meaning unclear to an agent.
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 clearly states the tool's function: returning a PNG of the controlled browser tab or native window. It specifies the resource and output type. It does not explicitly differentiate from sibling tools like computer_copy_image, but the purpose is unambiguous enough for an agent to infer its use.
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?
The description mentions a critical prerequisite (Screen Recording permission for native capture), which is a usage condition. However, it does not provide guidance on when to use this tool versus alternatives, nor does it state exclusions. The permission note is the only usage-related detail.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.