Xynaptic Crypto Movers — top gainers and losers 24h with volume filter (CoinMarketCap Pro): clean lists of real movers, not low-liquidity scams, with prices and % changes. GET (?limit=5). [price: $0.020 per call, x402/USDC]
| Name | Required | Description | Default |
|---|---|---|---|
| params | No | query parameters |
Changes observed during successful MCP inspections.
Input schema / properties / bodyRemoved value: -{
- "description": "JSON body for POST endpoints (e.g. insurance, ai-chat, production-risk)",
- "type": "object"
-}Input schema / properties / params / descriptionPrevious value: -"query parameters, e.g. {city: 'Paris', type: 'Appartement'}"New value: +"query parameters"Input schema / properties / params / propertiesAdded value: +{
+ "gainers": {
+ "description": "example: 5",
+ "type": "number"
+ },
+ "losers": {
+ "description": "example: 5",
+ "type": "number"
+ },
+ "top": {
+ "description": "example: {\"symbol\":\"BTC\",\"chg_24h\":3.2}",
+ "type": "string"
+ }
+}Input schema / requiredAdded value: +[]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It usefully discloses the upstream source (CoinMarketCap Pro), that low-liquidity tokens are filtered out, and the paid call model ($0.020 per call, x402/USDC), but it omits error behavior, rate limits, and pagination/return characteristics.
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?
It is a single dense sentence that front-loads the resource and scope, then adds source and pricing. Nothing is repeated, though the trailing GET/limit/price fragments read like appended metadata rather than a clean structure.
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?
No output schema or annotations exist, so the description must do more. It covers the source, filtering intent, and cost, but leaves parameter usage ambiguous and mismatched with the schema, and says nothing about response shape — adequate but with clear 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?
The description advertises a 'limit' query parameter, yet the schema exposes top/losers/gainers inside a nested params object — a mismatch that actively confuses rather than clarifies. Even with nominal 100% schema coverage, the inner schema fields are documented only by unhelpful example strings, so the description fails to make the parameters usable.
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 names a specific resource and scope: top gainers and losers over 24h with a volume filter, returning prices and % changes. It is clear what the tool produces, but it does not distinguish itself from similar siblings like crypto-market, crypto-screener, or crypto-price.
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?
There is no explicit when-to-use or when-not-to-use guidance, and no sibling is named as an alternative. Usage is only implied by words like 'movers' and 'gainers and losers'; an agent must guess whether this or crypto-market/crypto-screener is the right call.
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.