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

Annotations already declare destructiveHint=true and openWorldHint=true, so the agent knows this is a risky, environment-affecting action. The description usefully adds that this is a last-resort fallback and that it targets a pixel rather than a DOM node, but it says nothing about coordinate reference frame, retry/reliability behavior, or what gets clicked if the point is stale. Moderate added value on top of annotations.

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?

One sentence, front-loaded with "Fallback" so the routing signal arrives first, and every clause earns its place. No padding or restatement of the tool name.

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 values need no explanation. However, for a coordinate-based click with 0% schema description coverage and destructive annotations, the description leaves key operational gaps: the coordinate reference frame and the roles of button and job_id. Adequate but not sufficient for confident 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 description coverage is 0%, so the description must carry parameter meaning, and it only loosely covers x/y ("a visible point in a screenshot"). It never mentions the button enum (left/middle/right) or what job_id identifies, leaving two of four parameters undocumented anywhere. The coordinate-frame question (viewport vs page vs screenshot pixels) is also unanswered.

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 (click), the resource (a visible point in a screenshot), and the precise condition that defines this tool's niche: no accessible target is available. That condition is exactly what separates it from click_element and check_element, so an agent can route correctly without opening a schema.

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?

"Fallback ... when no accessible target is available" gives a clear when-to-use condition and implicitly names the alternative path (the accessible-element tools). It stops short of explicitly naming click_element or stating exclusions, so it is clear context rather than a full when/when-not routing rule.

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