screenshot

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

With no annotations present, the description carries the full burden and does real work: it discloses the return format (JPEG) and that the reply includes instructions for converting image coordinates to screen pixels, which directly enables follow-up tap/swipe calls. It omits capture scope (full screen vs. window) and any latency or permission considerations.

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, front-loaded with the action and format, followed by the selection rule. Every clause carries information an agent needs; no 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?

For a parameterless, annotation-free tool with no output schema, the description covers what matters most: what is returned and how to use the coordinates afterward. Missing is the capture scope and the distinction from browser_screenshot, which would make it fully self-sufficient.

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 there is no parameter semantics to explain and nothing the description needs to compensate for. Baseline of 4 applies.

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 ("Take a screenshot") plus the output format (JPEG), which an agent can act on immediately. It differentiates from read_screen, but says nothing about how it differs from the sibling browser_screenshot, leaving one plausible ambiguity unresolved.

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?

Gives an explicit when-to-use condition ("only when read_screen is not enough") with concrete examples (images, games, canvas UIs) and names the alternative tool. It stops short of an exclusion against browser_screenshot, so the routing guidance is strong but not exhaustive.

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