I used the same url for two different postings.
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"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so the description adds the cost information ($0.01 USDC) which is beyond annotations. However, it does not disclose other behavioral traits like rate limits or response format, but the output schema covers that. The description does not contradict annotations.
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?
The description is a single, front-loaded sentence that efficiently communicates the core action and cost. No wasted words, and it is appropriately concise for a simple tool.
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?
For a tool with two parameters and an output schema, the description is complete enough. It mentions the cost, and the output schema provides return structure. It does not elaborate on edge cases or limitations, but these are not critical for a straightforward extraction tool. The openWorldHint annotation suggests the tool may work broadly, which is consistent with the description.
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% for both parameters (url and schema), so the schema already documents them. The description adds minimal semantic value beyond stating 'structured JSON data' and does not clarify the optional schema parameter's purpose or format. Baseline of 3 is appropriate given high schema coverage.
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?
The description clearly states the tool extracts structured JSON data from web pages, using a specific verb and resource. It distinguishes itself from siblings like web_scraper and browser_scraper by specifying 'structured JSON' output, making its purpose unambiguous.
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?
The description provides no guidance on when to use this tool versus alternatives such as web_scraper or pdf_extractor. It does not mention prerequisites, typical use cases, or exclusions, leaving the agent to infer usage context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.