screenshot

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

With no annotations, the description carries the burden and does well: it discloses the return type (PNG image), that output may be scaled down for large screens, and that a graphical session is required. It omits what happens on failure or any latency/permission caveats beyond the session requirement.

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 sentences, fully front-loaded with the core action, no filler. The scaling note and coordinate-frame note each earn their place by preventing misuse.

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 parameterless capture tool with no output schema, the description supplies what an agent needs: what it returns, that the image may be resized, how the image relates to mouse coordinates, and the environment prerequisite.

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 tool takes zero parameters, so the baseline is 4; the description adds useful cross-tool meaning by defining the coordinate reference frame that sibling mouse tools consume. Nothing about parameters is missing because none exist.

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 a specific verb and resource (capture the screen of the server's machine) and names the return format (PNG, scaled down). It cleanly distinguishes itself from the sibling input tools by being the only capture/observation tool in the list.

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 states the prerequisite of a graphical session and ties itself to alternatives by noting that mouse_move_to and mouse_click_at use coordinates in this image's pixel space. It doesn't spell out a mandatory capture-before-click workflow, but the coordinate linkage gives clear implicit guidance.

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