veilbrowser

veil_use_frame

Redirect subsequent browser actions to a specific iframe by index, or return to the main page. Reacquire element refs after switching.

Instructions

Point every following veil_snapshot/veil_click/veil_fill/veil_type/veil_eval call at one child iframe (index from veil_frames), instead of the main page. Omit index (or pass null) to switch back to the main page. Existing refs are invalidated on switch — call veil_snapshot again after switching.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "veil_use_frame"
  }
}

Input Schema

Name	Required	Description	Default
`index`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.5.0Jul 29, 2026

TDQS

A4.7/5.0

Behavior4/5

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

With no annotations, the description carries full burden for behavioral disclosure. It reveals that switching invalidates existing references and requires re-snapshotting. This is valuable context, though it could mention if there are any side effects or error conditions. Still, it adds significant value beyond the schema.

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 concise sentences, front-loaded with the primary action, then detailed consequences. Every word serves a purpose with no repetition or fluff.

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

Completeness5/5

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

Given the tool's simplicity (one parameter, no output schema), the description fully covers essential context: which tools are affected, how to switch back, and the need to re-snapshot. It is complete for proper usage.

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

Parameters4/5

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

The only parameter 'index' is described as the child iframe index from veil_frames, with null meaning main page. Schema description coverage is 0%, so the description compensates by providing clear meaning and usage, which is necessary for correct invocation.

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?

The description clearly states the tool's purpose: to point subsequent veil_* calls at a child iframe instead of the main page. It specifies the affected sibling tools (veil_snapshot, veil_click, etc.) and distinguishes itself by focusing on frame targeting, setting it apart from other tools.

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

Usage Guidelines5/5

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

Explicitly explains when to use: after obtaining frame indices from veil_frames, and how to switch back to main page by omitting or passing null. Also notes that existing refs are invalidated on switch, requiring a fresh veil_snapshot call, providing clear when-not and post-conditions.

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