Executes a SELECT query against a ClickHouse service. Runs a read-only SELECT query on the specified ClickHouse service via the Query API endpoint. This function provides direct access to database content through SQL queries while ensuring that only read operations are permitted.
Risk signalsAccepts freeform code/query input (query)
Part of the ClickHouse server.
Free to start. No card required.
AI agents invoke run_select_query to trigger processes or run actions in ClickHouse. Execute operations can have side effects beyond the immediate call -- triggering builds, sending notifications, or starting workflows. Rate limits and argument validation are essential to prevent runaway execution.
run_select_query can trigger processes with real-world consequences. An uncontrolled agent might start dozens of builds, send mass notifications, or kick off expensive compute jobs. PolicyLayer enforces rate limits and validates arguments to keep execution within safe bounds.
Execute tools trigger processes. Rate-limit and validate arguments to prevent unintended side effects.
{
"version": "1",
"default": "deny",
"tools": {
"run_select_query": {
"limits": [
{
"counter": "run_select_query_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}See the full ClickHouse policy for all 15 tools.
These attack patterns abuse exactly the kind of access run_select_query gives an agent. Each links to the full case and the policy that stops it:
Other execute tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Executes a SELECT query against a ClickHouse service. Runs a read-only SELECT query on the specified ClickHouse service via the Query API endpoint. This function provides direct access to database content through SQL queries while ensuring that only read operations are permitted.. It is categorised as a Execute tool in the ClickHouse MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the ClickHouse MCP server in PolicyLayer and add a rule for run_select_query: 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 ClickHouse. Nothing to install.
run_select_query 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 run_select_query 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 run_select_query. 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.
run_select_query is provided by the ClickHouse MCP server (@ClickHouse/mcp-clickhouse). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 15 ClickHouse tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.