List all available parquet files that can be queried with SQL USAGE NOTES: - This function lists parquet files that have already been downloaded - Each file can be queried using read_parquet('/path/to/file.parquet') in your SQL - For each file, this returns the file path, dataset type, and other ...
AI agents call list_available_sql_tables to retrieve information from Cryo MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a pure query/listing operation that retrieves metadata about available data sources. It has no side effects, does not execute code or queries, and does not modify data. The highest blast radius would be information disclosure of available datasets, which is low risk in a blockchain data extraction context where such data is typically public.
From the tool's definition Tool lists parquet files and returns metadata; described as 'List all available parquet files' with return of 'file paths, dataset type, and other metadata'. No modification, deletion, or execution occurs.
Documented attack patterns abuse exactly the kind of access list_available_sql_tables gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Cryo MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_available_sql_tables:
{
"version": "1",
"default": "deny",
"tools": {
"list_available_sql_tables": {}
}
}list_available_sql_tables is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all available parquet files that can be queried with SQL USAGE NOTES: - This function lists parquet files that have already been downloaded - Each file can be queried using read_parquet('/path/to/file.parquet') in your SQL - For each file, this returns the file path, dataset type, and other metadata - Use these file paths in your SQL queries with query_sql() Returns: List of available files and their metadata. It is categorised as a Read tool in the Cryo MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Cryo MCP Server MCP server in PolicyLayer and add a rule for list_available_sql_tables: 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 Cryo MCP Server. Nothing to install.
list_available_sql_tables 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_available_sql_tables 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_available_sql_tables. 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_available_sql_tables is provided by the Cryo MCP Server MCP server (z80dev/cryo-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 10 Cryo MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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10 Cryo MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.