Mcp-DOM

by IrMaho

Overview Schema Source Related Servers Discussions Admin

TypeScript

Local

get_live_dom_subtree

Extract the live HTML structure of any DOM subtree on the active browser page using a node ID or CSS selector.

Instructions

Reconstruct and extract the live HTML or node structure of a specific subtree on the active browser page.

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": "get_live_dom_subtree"
  }
}

Input Schema

Name	Required	Description	Default
`nodeId`	No	LogicalNodeId of the subtree root
`selector`	No	CSS selector of the subtree root

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Sep 1, 2026

TDQS

A3.5/5.0

Behavior2/5

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

No annotations are provided, so the description must carry the full behavioral transparency burden. It hints at read-only extraction but does not explicitly state side effects, freshness guarantees beyond 'live', output format, or behavior when the subtree cannot be found.

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?

The description is a single, well-structured sentence with no filler. The key terms 'live HTML', 'node structure', and 'specific subtree' are front-loaded and immediately tell the agent what the tool operates on.

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?

For a relatively simple tool with only two documented parameters, the description gives enough initial scoping, but important gaps remain: there is no output schema, no detail on the returned HTML/node representation, and no guidance on how to resolve the ambiguity of two optional identifying parameters (nodeId vs selector).

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%, and nodeId and selector are already clearly described as the subtree root. The description does not add additional meaning about how these parameters interact, which one is preferred, or what happens if both are omitted, so the baseline score of 3 is appropriate.

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 states a specific action (reconstruct and extract), a clear resource (live HTML or node structure of a subtree), and a clear scope (active browser page). It also differentiates from sibling tools by combining 'live' and 'specific subtree', helping distinguish it from get_dom_subtree and get_live_dom_napshot.

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?

The description implies when it should be used—when a specific live subtree is needed—but offers no explicit guidance on when to choose this over get_dom_subtree, get_dom_node, or get_live_dom_snapshot. No alternatives or exclusions are mentiond.

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