page_expectVisible

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

With no annotations, the description fully carries the burden of behavioral disclosure. It states that the tool does not check visual visibility, does not poll, never throws errors, and returns a specific shape ({pass, expected, actual, snapshot}). It also discloses the limitation regarding custom component penetration.

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?

The description is relatively long but every sentence adds important information. It is front-loaded with the core purpose. Minor redundancy could be trimmed, but overall it's well-structured and concise for the amount of detail provided.

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?

Given no annotations or output schema, the description is fairly comprehensive. It covers purpose, behavior, return format, and limitations. It could be improved by explicitly listing all return fields, but the snapshot structure is hinted. The connection parameter is not justified in the description.

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?

The description adds meaning to the 'selector' parameter by explaining how it works (based on page.$$ hit counts and optional [index=N] syntax). The 'connection' parameter is already described in the schema, but the description does not add extra semantics for it. Overall, it compensates for missing schema description on the required parameter.

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?

The description clearly states the tool's purpose: an assertion for whether a selector can locate elements on the page, based on page.$$ hit count or index range. It distinguishes itself from sibling tools like page_expectCount, page_expectElementText, etc., by focusing specifically on existence/locatability.

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?

The description explicitly explains when to use this tool (for existence checks only) and when not to use it (e.g., for visual visibility or for elements inside custom components). It provides alternatives: 'element_getInnerElements' for inner component elements, implying other tools for visual checks.

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