ui_take_annotated_screenshot

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

Annotations indicate idempotent and read-only behavior. Description adds detail: returns WebP image with compact index, and explains compact mode saves ~60KB. No contradictions.

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?

Concise, well-structured: purpose sentence, return info, usage tip, then parameter list. Every sentence adds value 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?

Covers return format and key behavioral details. No output schema, but description sufficiently describes outputs. Could mention image encoding, but not critical for selection.

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?

All 5 parameters are described with their effect (max_depth, interactive_only, max_width, format, compact). Schema coverage is 0%, so description compensates fully.

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?

Clearly states the tool's purpose: taking a screenshot with numbered UI elements overlaid (Set-of-Mark pattern). Distinguishes from sibling tools like ui_take_screenshot and ui_click_annotated.

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?

Provides clear usage context: obtain annotated screenshot, then use ui_click_annotated to interact. Does not explicitly exclude alternative tools, but the use case is well-defined.

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