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

No annotations exist, so the description carries the full burden. It does disclose a real behavioral trait no schema exposes: the call costs 1 mcp_call, and coordinates are relative to a resized viewport, a state dependency that affects correctness. It omits, however, whether a session must be open, what happens on click failure, or whether the click can trigger navigation.

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?

Two short sentences, zero padding, with the coordinate constraint front-loaded before the cost note. Brevity is achieved, though at the cost of the parameter and session explanation the agent actually needs.

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 3-parameter tool with 0% schema coverage, no annotations, and no output schema, the description is too thin: coordinate origin, session targeting, and failure behavior are all unaddressed. The only compensating detail is the mcp_call cost.

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 compensate and largely does not. It clarifies that x/y are pixels rather than CSS selectors or offsets, but gives no origin corner or unit convention, and the third parameter "session" (default "default") is never mentioned at all, leaving the agent unaware that a session can be targeted.

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 plus resource ("Click") qualified by an explicit input domain ("pixel coordinates of the (resized) viewport"), which implicitly separates it from the selector-based sibling browser_click. It never names that sibling, so the differentiation is inferable rather than stated.

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?

There is no explicit guidance on when to prefer coordinate clicking over browser_click, no prerequisites such as an active session or a prior navigate/screenshot step, and no exclusions. The agent must reconstruct the decision rule from the phrase "pixel coordinates" alone.

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