mcp-toolbelt

structured_data_extract

Fetch a URL and extract structured data deterministically: JSON-LD blocks (each one also VALIDATED — @context/@type presence plus required fields for common schema.org types like Article, Product, Organization, FAQPage), OpenGraph/meta tags, and optional caller-supplied CSS-selector fields (e.g. { price: '.product-price', title: 'h1' }). No LLM involved — pure HTML parsing via CSS selectors, so results are exact matches only, not summarized or inferred. For a whole-page SEO audit (headings, links, images, meta lengths) use seo_audit instead.

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": {
      "url": "<url>"
    },
    "name": "structured_data_extract"
  }
}

Input Schema

Name	Required	Description
`url`	Yes	The URL to extract from
`attr`	No	Optional HTML attribute to extract instead of text content (e.g. 'href', 'src', 'content'). Applies to all selector fields in this call.
`selectors`	No	Optional map of field name -> CSS selector (e.g. { price: '.product-price', headline: 'h1' }). Each field returns an array of matched, whitespace-normalized text values in document order.

Schema Changelog

Changes observed during successful MCP inspections.

First observedAug 31, 2026

TDQS

A4.1/5.0

Behavior4/5

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

With no annotations, the description carries the full burden and does well: it discloses that no LLM is involved, that results are deterministic exact matches (not summarized or inferred), and that JSON-LD blocks are actively VALIDATED against @context/@type and required fields. It omits operational traits like fetch/rate-limit or auth behavior, keeping it short of a 5.

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?

Well front-loaded: the core action and its outputs come first, and the seo_audit reroute closes the paragraph. It is slightly verbose in restating the selector example that the schema already provides, which costs a point.

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

Completeness4/5

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 must carry the return-value burden, and it does describe what comes back (JSON-LD, meta tags, selector-field arrays) and the validation behavior. It is close to complete for a read-only extraction tool, missing only edge-case behavior on fetch failure or empty matches.

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 the schema already documents all three parameters including attr and selectors. The description repeats the selector-map example already present in the schema and adds no syntax or format detail beyond it, so the baseline 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?

States a specific verb+resource ('Fetch a URL and extract structured data') and enumerates exactly what it extracts: validated JSON-LD blocks, OpenGraph/meta tags, and optional caller-supplied CSS-selector fields. It distinguishes itself from siblings by naming seo_audit as the tool for whole-page SEO auditing.

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?

Explicitly routes the agent to seo_audit for whole-page SEO audits, giving clear when-to-use guidance with an alternative. However, it does not address the potential confusion with the sibling url_to_markdown, which also transforms page HTML, so the alternative coverage is incomplete.

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

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