Get available cryptocurrencies with optional amount filtering. USE WHEN: (1) User asks which cryptos available, (2) BEFORE onchain payment if crypto has multiple networks (e.g., USDC). DISPLAY RULES: Show users
AI agents call list_currencies_catalog to retrieve information from Sperax Ecosystem Crypto & DeFI MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries a catalog of available cryptocurrencies with optional filtering. It performs no modifications, deletions, or financial transactions—merely returns data about what cryptocurrency options exist on the Sperax ecosystem. No irreversible or side-effect operations occur. Classification as Read is appropriate.
From the tool's definition Tool name 'list_currencies_catalog' and description 'Get available cryptocurrencies' indicate a query/retrieval operation with no side effects.
Documented attack patterns abuse exactly the kind of access list_currencies_catalog gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Sperax Ecosystem Crypto & DeFI MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_currencies_catalog:
{
"version": "1",
"default": "deny",
"tools": {
"list_currencies_catalog": {}
}
}list_currencies_catalog is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get available cryptocurrencies with optional amount filtering. USE WHEN: (1) User asks which cryptos available, (2) BEFORE onchain payment if crypto has multiple networks (e.g., USDC). DISPLAY RULES: Show users. It is categorised as a Read tool in the Sperax Ecosystem Crypto & DeFI MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Sperax Ecosystem Crypto & DeFI MCP Server MCP server in PolicyLayer and add a rule for list_currencies_catalog: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Sperax Ecosystem Crypto & DeFI MCP Server. Nothing to install.
list_currencies_catalog is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list_currencies_catalog rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for list_currencies_catalog. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
list_currencies_catalog is provided by the Sperax Ecosystem Crypto & DeFI MCP Server MCP server (sperax/sperax-crypto-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Sperax Ecosystem Crypto & DeFI MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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1318 Sperax Ecosystem Crypto & DeFI MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.