nex_browser_mouse_click_xy

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

With no annotations, the description carries the full burden; it does disclose the coordinate space, the surfaces covered, the out-of-scope native toolbar popups, and prohibited CAPTCHA workarounds. It says nothing about preconditions (active session/page), whether the click waits for stability, or what happens on a failed hit, which matters for a raw-coordinate mutation.

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?

Front-loaded with the action, then coordinate derivation, then the CAPTCHA routing — each sentence adds distinct information. The prose is dense and clause-heavy (parentheticals, embedded formulas), which slightly hurts scanability but there is no 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?

For a 7-parameter click tool with no annotations and no output schema, the definition covers coordinate sourcing and CAPTCHA policy well but leaves the sibling-selection question and half the parameters unaddressed. An agent knows the coordinate math yet still can't tell confidently why it would use this instead of nex_browser_click.

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?

Coverage is 29% — only pageId and sessionId are documented in the schema — but the description supplies the crucial semantic for x/y (CSS pixels in the viewport) and the pixelsPerCssPixel/origin conversion for turning screenshot pixels into them. The remaining parameters delay, button and clickCount get no treatment at all.

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 verb and coordinate system: click at x/y in viewport CSS pixels, and enumerates the surfaces it reaches (canvas, iframes, extension overlays) while excluding native toolbar popups. However, it never names the obvious sibling nex_browser_click (selector-based), so an agent still has to infer which clicking tool to pick.

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?

It gives one explicit routing rule — for page CAPTCHAs start with nex_browser_captcha_prepare and do not use CDP/Python/image matching/scripted drags — plus the requirement to derive coordinates from a fresh screenshot. It never says when to prefer this tool over nex_browser_click, which is the most consequential usage decision here.

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