create_virtual_display

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already convey safety hints (readOnlyHint=false, destructiveHint=false). The description adds useful behavioral detail: it runs a real X server without a physical screen and returns a JSON with pid, which helps the agent understand the side effects and result. It does not mention cleanup or failure conditions, but that is acceptable given the annotation coverage.

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 efficient and well-structured: two impactful opening sentences establish purpose and use case, followed by structured Args and Returns sections. Every sentence carries information without redundancy.

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 description covers what the tool does, what inputs it takes, and what it returns. It does not explain how to interact with the created display using other tools (e.g., launch_on_virtual_display), but that is beyond the scope of a creation tool. The output schema exists, so the return format is already documented.

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 for the top-level 'params' parameter is 0% (no description on that property). The description compensates by explicitly listing the contained fields: 'display number, width, height, depth'. The return example also illustrates the format (e.g., ':99' and '1280x800x24'), adding semantic context beyond the raw schema.

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 opens with a specific verb and resource: 'Start an Xvfb virtual display'. It clearly distinguishes itself from sibling tools like create_headless_desktop by describing itself as the 'Linux counterpart of the Windows headless desktop'.

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 provides clear context for when to use the tool: when GUI apps need headless execution with automation (xdotool) and screenshots (mss) on Linux. It implicitly contrasts with the Windows headless desktop, but does not explicitly name alternatives or state exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.