tool_element_at_point

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

With no annotations, the description carries the full burden. It explicitly states 'Read-only — moves no cursor and changes no focus', which is a key behavioral disclosure. It also mentions the return of an opaque ref. It doesn't cover error conditions or edge cases like no element at the point, but for a read-only query the main behavioral trait is disclosed.

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, with no filler. The core purpose is front-loaded, followed by return values and the crucial coordinate-space clarification, and ends with a safety note. 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?

The tool has only two parameters and an output schema, so the description doesn't need to explain return values. It covers the use case, coordinate space, and read-only behavior. The only minor gap is not addressing the case where no element exists at the point, but the output schema likely handles that. Overall it is complete enough for correct invocation.

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 coverage is 0%, so the description must compensate. It explains that x and y are physical pixel coordinates in the same space as capture bounds, which is critical for correct usage. It also emphasizes 'PHYSICAL screen point' to avoid coordinate-space ambiguity. This adds meaning well beyond the bare integer type in the schema.

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 ('Identify') and resource ('UI element at a PHYSICAL screen point via Windows UI Automation'), then lists exactly what is returned (name, role, rect, supported actions, opaque ref). It also distinguishes itself from siblings by framing it as the way to turn a screenshot point into an addressable element without clicking, clearly separating it from click_at and read_element.

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 states when to use it: when you have a physical screen coordinate from a screenshot and want to address the element without clicking. It notes the coordinate space matches capture bounds. It does not explicitly name alternatives or state when not to use it, but the purpose is clear enough that an agent can infer it is the right tool for point-based element lookup.

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