where

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

Annotations already declare readOnly/idempotent/non-destructive, and the description remains consistent while adding real context: results come from the "latest map of its interface" and no live navigation occurs, so the agent knows the answer may be a snapshot. It stops short of saying what happens on a miss or how stale the map can be.

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 core behavior and the no-navigation caveat are front-loaded, and the Args block is tight and example-driven. Dense jargon ("relay landmark", "debugging port") costs a little readability but no sentence is filler.

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?

An output schema exists, so return shape needn't be spelled out, and the description nonetheless previews the returned fields. For a 2-param read-only lookup this is nearly sufficient; only failure/not-found behavior is left unaddressed.

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% (only bare titles "App" and "What"), so the description carries the burden and does it well: it constrains app to "codex" or "antigravity" and lists the accepted identifier forms for what (label, aria-label, data-* attribute, translation key, landmark name) with concrete examples. Minor gap: no statement of matching precedence or case sensitivity when multiple forms could match.

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?

States a specific resource (a button/menu's location in Codex or Antigravity) and enumerates exactly what is returned: path, landmark, stable attributes, gestures. An agent can tell this is a UI-element lookup tool distinct from action siblings like send/close/read. It doesn't name a sibling to contrast with, which keeps it from a 5.

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?

"No navigation: only the stored map is read" sets a boundary on what the tool will do, which implies the usage context, but it never states when to prefer this tool over e.g. survey or status, nor any prerequisites. Usage is inferred rather than directed.

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