screenshot

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

With no annotations provided, the description carries the full burden and does more than restate the name. It discloses output optimization, optional grid/compression/cropping behaviors, and a perceptual bias caveat. It stops short of detailing error behavior or what happens with invalid window IDs, but for a read-only capture tool this is strong disclosure.

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 compact and front-loaded. Every sentence earns its place: scope, output orientation, routing to the preferred alternative, and a practical positional correction. There is no filler or unnecessary repetition.

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-required-parameter tool with full schema coverage, the description is nearly complete. It covers what the tool does, when to use it, what to prefer instead, and a useful visual bias tip. The main omission is distinguishing explicitly from screenshot_annotated among the siblings, plus minor edge-case behavior for windowId.

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 description coverage is 100%, so the baseline of 3 applies. The description's mention of grid overlay, compression, and region cropping essentially paraphrases schema properties without adding new semantic detail such as coordinate conventions or interaction between parameters.

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: 'Take a screenshot of the entire screen or a specific region.' It also clarifies the output purpose ('optimized for AI analysis') and distinguishes the tool from ai_screen_elements, which is for finding clickable elements. This makes the tool's purpose unambiguous and differentiates it from key siblings.

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?

Usage guidance is explicit: prefer ai_screen_elements when clickable elements are needed, use screenshot only for a raw visual overview or verification, and even warns about visual Y-axis estimation bias. This tells the agent exactly when to choose this tool and when to select an alternative.

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