Verify an element's presence, visibility, enabled or disabled state, focus, editability, selection, or viewport status by selector, text, or class name before interacting.
Unified check of element status (exists/visible/hidden/enabled/disabled/checked/focused/editable/in_viewport)
| Name | Required | Description | Default |
|---|---|---|---|
| text | No | Check text exists | |
| state | No | ||
| timeout | No | ||
| selector | No | ||
| class_name | No | Check class name |
Changes observed during successful MCP inspections.
v4.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden, and it says nothing about what the tool returns (boolean vs. raise/throw on failure), how timeout interacts with the check, or whether it auto-waits/retries. For a verification tool whose entire contract is the shape of its result, this is a significant gap.
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?
A single compact sentence with the state list in a parenthetical – front-loaded and free of filler. It is arguably under-specified rather than verbose, but structurally it is tight.
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 no annotations, no output schema, and only 40% param coverage, the description should explain the return contract and how the check behaves on failure. It omits all of this, leaving the agent unable to interpret results.
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 only 40%, with five parameters and undocumented selector, state, and timeout entries. The description merely mirrors the state enum already present in the schema and adds nothing about selector vs text vs class_name precedence or timeout semantics, so it fails to compensate for the coverage gap.
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 (check) and resource (element status) and enumerates the nine states it can evaluate, which is more precise than a vague 'check element'. However, it never differentiates itself from siblings that appear to do overlapping things (exists, is_visible, assert), so an agent cannot tell when this unified tool should win.
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 when-to-use guidance at all. With siblings exists, is_visible, wait_for, assert, and find all plausibly covering the same ground, the description should say when to prefer this unified check over those specific tools, and it does not.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.