Click

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

Annotations already declare readOnlyHint=false and openWorldHint=true, so the mutation/open-world nature is known. The description adds genuinely useful behavior beyond that: the response reports what changed on screen rather than returning a new snapshot, which tells the agent not to expect a full page dump and not to follow up with browser_snapshot reflexively.

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?

Three compact sentences with zero filler: the action first, the constraint second, the response shape last. Every sentence carries distinct information and nothing is repeated from the schema or annotations.

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?

With only two fully documented parameters, no output schema, and annotations covering safety, the description supplies exactly the remaining pieces an agent needs: the ref-only requirement and the diff-style return behavior. Nothing material is missing 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 100%, so both ref and double are already documented in structured fields. The description reinforces the ref-only constraint but does not add syntax or format detail, and the double-click parameter is covered solely by the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

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) and resource (an element by its ref), and enumerates the element types covered: link, button, checkbox, tab, menu item. That enumeration also separates it from siblings like browser_type, browser_select, and browser_key without needing the schemas.

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?

"Refs only, not CSS selectors or text" is an explicit negative constraint that rules out a common wrong invocation, and the schema points to where refs come from (latest view or browser_find). It stops short of naming which sibling to use for non-click interactions (typing, selecting), so it is clear context but not full alternative routing.

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