describe_ui

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

No annotations are provided, so the description carries the burden. It thoroughly discloses the output structure (wireframe, element inventory, visual notes), making the tool's behavior clear. However, it does not mention potential input restrictions or error handling for the path parameter, which leaves a minor gap.

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, each earning its place. The first packs in the full output format, the second provides guidance on when to use the tool. No wasted words.

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 one-parameter analysis tool, the description provides enough context to understand what the tool returns and when to use it. The output schema exists but is not shown, so the textual description of output components is helpful. However, the lack of any explanation about the path parameter slightly reduces completeness.

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 schema has a single 'path' parameter with no description (0% schema description coverage). The tool description never mentions the path parameter, so it does not compensate for the missing schema detail. The agent must infer from the tool name and general context that 'path' refers to a screenshot file, but no explicit format or constraints are given.

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 tool produces a structured UI report for a screenshot, explicitly listing the output components (ASCII layout wireframe, element inventory with positions and states, visual notes). It also distinguishes itself from the sibling tool describe_image by referencing specific use cases.

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 explicitly says 'Prefer this over describe_image when you need layout, element positions and states rather than general prose.' This gives direct, actionable guidance on when to choose this tool over the alternative.

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