AI agents invoke refresh_catalog to trigger actions in Snowflake MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool triggers an external operation (refreshing/rebuilding the internal schema catalog cache), which goes beyond a simple read. It causes a side effect by invalidating and repopulating cached data. However, it does not delete or modify warehouse data, so it is not Destructive or Write. It executes an administrative operation whose effect is updating the cache state.
From the tool's definition Refresh the schema catalog cache
Documented attack patterns abuse exactly the kind of access refresh_catalog gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Snowflake MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for refresh_catalog:
{
"version": "1",
"default": "deny",
"tools": {
"refresh_catalog": {
"limits": [
{
"counter": "refresh_catalog_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}refresh_catalog stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Refresh the schema catalog cache. It is categorised as a Execute tool in the Snowflake MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Snowflake MCP Server MCP server in PolicyLayer and add a rule for refresh_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 Snowflake MCP Server. Nothing to install.
refresh_catalog is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the refresh_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 refresh_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.
refresh_catalog is provided by the Snowflake MCP Server MCP server (ncejda-g2/snowflake_mcp_server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Snowflake 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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7 Snowflake MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.