screenshot

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states that the tool returns a JPEG and describes the intended frequency of use, which communicates its passive/read-only nature. It does not explicitly say 'does not affect the screen,' but the semantics of taking a screenshot make this clear enough for an agent.

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, purposeful sentences with no filler. The core action and output are front-loaded in the first sentence, and the usage guidance follows naturally. Every sentence earns its place.

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 zero-parameter, no-output-schema tool, the description is complete: it states what the tool does, what it returns, and how often to use it. There is no missing information that an agent would need to invoke it correctly based on the provided context.

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 has zero parameters and schema coverage is effectively complete, so there is nothing for the description to add about individual arguments. The baseline for zero-parameter tools is 4, and the description does not create any confusion about inputs by omitting them.

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 action ('Take a screenshot'), the resource ('current state of the screen'), and the output format ('JPEG image'). It is immediately distinguishable from the sibling tools, which are all input actions like clicks, keys, and mouse movement; this one is observational and returns visual data.

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 gives explicit when-to-use guidance: 'Call this frequently to observe what is on screen.' This tells the agent this is the primary observation tool in the set. It does not explicitly name when not to use it or mention alternatives, but the sibling list contains no other screen-observation tool, so this omission is minor.

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