find_on_screen

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

With no annotations provided, the description carries the full burden. It discloses the internal search strategy ('Searches XML elements first (fast), falls back to OCR if not found') and the return behavior ('Returns JSON with {text, x, y, w, h, method} or null if not found'). This is rich behavioral context.

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 concise: four sentences, each adding value. It starts with the main purpose, then implementation detail, usage guidance, and return format. No redundant or filler content.

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 simple 2-parameter tool with an output schema, the description is complete. It covers purpose, usage, search method, return format, and null behavior. The existence of an output schema reduces the need to describe return values, yet the description does anyway for clarity.

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 0%. The description implies the 'text' parameter ('Find specific text') but does not explain the 'device' parameter at all. The agent is left to infer what 'device' means, making invocation potentially ambiguous. The description should at least mention that device targets the device.

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's purpose: 'Find specific text on the screen and return its location.' It identifies the resource (screen text) and the specific action (find and return location), distinguishing it from sibling tools like get_screen_tree or ocr_screen.

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 provides a clear usage context: 'Use this to check if a button, label, or message is visible.' This tells the agent when to invoke the tool. However, it does not explicitly mention alternatives or when not to use it, so it earns a 4 rather than a 5.

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