I used the same url for two different postings.
Extracts plain text preview from public PDF URLs ($0.005 USDC)
| Name | Required | Description | Default |
|---|---|---|---|
| pdfUrl | Yes | Public HTTPS URL of the target PDF document |
| Name | Required | Description | Default |
|---|---|---|---|
| pages | No | Number of pages parsed | |
| success | Yes | Parsing status | |
| textPreview | Yes | Extracted plain text body |
Changes observed during successful MCP inspections.
Input schema / properties / pdfUrl / descriptionAdded value: +"Public HTTPS URL of the target PDF document"Output schema / (root)Previous value: -nullNew value: +{
+ "properties": {
+ "pages": {
+ "description": "Number of pages parsed",
+ "type": "integer"
+ },
+ "success": {
+ "description": "Parsing status",
+ "type": "boolean"
+ },
+ "textPreview": {
+ "description": "Extracted plain text body",
+ "type": "string"
+ }
+ },
+ "required": [
+ "success",
+ "textPreview"
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the annotations (read-only, idempotent, open-world), the description adds meaningful behavioral detail: it returns only a 'plain text preview' rather than full content or layout, it requires a public URL, and it costs $0.005 USDC. This gives the agent useful expectations beyond the structured hints.
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 conveys the action, the input type, the output nature, and the cost without any filler. Every element earns its place.
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 single-parameter tool with full schema coverage, annotations, and an output schema present, the description provides enough context: what it does, what input it accepts, the preview nature of the result, and the cost. Nothing critical is missing for correct selection and invocation.
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?
The input schema already documents the only parameter ('pdfUrl') clearly: 'Public HTTPS URL of the target PDF document'. Since schema description coverage is 100%, the description adds little parameter-specific meaning beyond emphasizing the public PDF scope already present in the schema.
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 identifies a specific action ('Extracts plain text preview') and a specific resource type ('public PDF URLs'). It is clear and unambiguous, though it does not explicitly contrast itself with sibling scraping tools like web_scraper or browser_scraper.
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 target input is clearly framed as a public PDF URL, which implies this tool is for PDFs rather than general web pages. However, it does not explicitly state when to prefer this over siblings or mention alternatives, leaving the routing decision partially to inference.
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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