veilbrowser

veil_wait_for_selector

Polls the page until a CSS selector matches, with an optional requirement for visibility. Returns when the element is found or times out with an error.

Instructions

Poll until a CSS selector matches, then return (the selector-shaped convenience over veil_wait_for). Pass visible:true to also require the element to be laid out and not display:none/visibility:hidden. Errors on timeout.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "selector": "<selector>"
    },
    "name": "veil_wait_for_selector"
  }
}

Input Schema

Name	Required	Description
`timeout`	No	ms before giving up (default 10000)
`visible`	No	also require the element to be visibly rendered (default false)
`selector`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.5.0Jul 29, 2026

TDQS

A4.1/5.0

Behavior4/5

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

No annotations provided, but description conveys polling behavior, return on match, timeout error, and visibility condition. Lacks detail on polling interval or side effects, but sufficient for a read-type wait operation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two efficient sentences, no redundancy, front-loads key purpose. Every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema, so return value is implied but not specified ('then return' lacks detail). Polling behavior is partially described. For a simple wait tool, missing return description reduces completeness.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 67%; description adds context for visible parameter but not for selector. Timeout explanation is partially overlapped. Baseline 3 due to partial schema coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Description clearly states it polls until a CSS selector matches, then returns. It differentiates from sibling veil_wait_for as a 'selector-shaped convenience', providing specific verb and resource.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Mentions when to use (wait for CSS selector), optional visible:true flag for visibility checks, and error on timeout. Implicitly considers veil_wait_for as alternative but lacks explicit when-not-to-use guidance.

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