Extracts structured JSON data from web pages ($0.01 USDC)
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | Target website URL to extract schema data from | |
| schema | No | Optional extraction target schema |
| Name | Required | Description | Default |
|---|---|---|---|
| success | Yes | Extraction status | |
| extractedData | Yes | Structured JSON output |
Changes observed during successful MCP inspections.
Input schema / properties / schemaAdded value: +{
+ "description": "Optional extraction target schema",
+ "type": "object"
+}Input schema / properties / url / descriptionAdded value: +"Target website URL to extract schema data from"Output schema / (root)Previous value: -nullNew value: +{
+ "properties": {
+ "extractedData": {
+ "description": "Structured JSON output",
+ "type": "object"
+ },
+ "success": {
+ "description": "Extraction status",
+ "type": "boolean"
+ }
+ },
+ "required": [
+ "success",
+ "extractedData"
+ ],
+ "type": "object"
+}Input schema / properties / schemaRemoved value: -{
- "type": "object"
-}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, and idempotentHint=false, so safety is covered. The description adds genuinely useful context the annotations lack: the $0.01 USDC cost per call, which matters for an agent deciding whether to invoke it. It stops short of explaining payment mechanics or rate limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single front-loaded sentence with zero filler; the cost is appended compactly in parentheses. Very efficient, though extremely terse relative to the tool's complexity.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
An output schema exists so return values need no explanation, and annotations cover safety. But for a paid, open-world extraction tool with a nested schema parameter, the description omits usage guidance and any payment/auth mechanics, leaving meaningful gaps.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so both url and schema parameters are already documented in the schema. The description adds nothing about the schema parameter's format or how extraction targets are specified, so the baseline 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb (extracts) and resource (structured JSON data from web pages), which is clear and distinguishable from pdf_extractor or web_scraper by the structured-JSON output framing. However, it does not explicitly differentiate itself from sibling scraping tools like browser_scraper or web_scraper, which would be needed for a 5.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No indication of when to use this over web_scraper, browser_scraper, or pdf_extractor, nor any prerequisites (e.g., payment, auth). The agent must infer usage from the name alone.
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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