BrowserMCP Extended

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browser_execute_in_frame

Execute JavaScript code within a targeted iframe using its frame ID, HTML id, or name to inspect or modify embedded page content.

Instructions

Execute JavaScript code inside a specific iframe

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": {
      "frameId": "<frameId>",
      "code": "<code>"
    },
    "name": "browser_execute_in_frame"
  }
}

Input Schema

Name	Required	Description	Default
`code`	Yes	JavaScript expression to evaluate in the frame
`frameId`	Yes	Target frame ID, HTML id attribute, or name

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Nov 2, 2026

TDQS

B3.1/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden. It doesn't state that arbitrary code execution is a powerful, potentially destructive operation, doesn't mention cross-origin/sandbox restrictions on frames, and doesn't say whether the evaluation result is returned.

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

Conciseness4/5

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

A single front-loaded sentence with no filler. It is efficient, though the brevity borders on under-specification for a code-execution tool.

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

Completeness2/5

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

With no annotations and no output schema, the description should explain what happens to the evaluated result and any frame-access limitations. Neither is covered, leaving the agent unsure how to interpret success or failure.

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 description coverage is 100%, so both frameId and code are fully documented in the schema. The description adds no syntax or format detail beyond that, so the baseline 3 applies.

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

Purpose4/5

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

States a specific verb and resource: execute JavaScript inside a specific iframe. 'Specific iframe' implicitly contrasts with the top-level execute_script sibling, though that sibling is never named.

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

Usage Guidelines3/5

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

Usage is only implied by the word 'iframe' – an agent can infer this is for frame-scoped script execution rather than page-level execution. There is no explicit when-to-use or when-not-to-use guidance and execute_script is not mentioned as the alternative.

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