run_dcl_query

THE RISK

High Risk

Why run_dcl_query needs a policy

DCL queries modify database access control and permissions. While technically reversible (REVOKE can undo GRANT), they represent execution of system-level commands that alter security boundaries. This is more severe than Write (which typically modifies data) but distinct from Destructive (which is data deletion).

From the tool's definition Tool description explicitly states 'Run a raw DCL SQL query, like GRANT, REVOKE, etc.' DCL (Data Control Language) commands control permissions and access rights in PostgreSQL.

Documented attack patterns abuse exactly the kind of access run_dcl_query gives an agent:

POLICY

How to control run_dcl_query

PolicyLayer is an MCP gateway — it sits between your AI agents and Pgsql, and nothing reaches the server without passing your rules. This is the rule we recommend for run_dcl_query:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "run_dcl_query": {
      "limits": [
        {
          "counter": "run_dcl_query_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

run_dcl_query 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.

Create a free account and register Pgsql — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Pgsql tools

Destructive run_ddl_query Run a raw DDL SQL query, like CREATE, ALTER, DROP, etc. Destructive run_dml_query Run a raw DML query, like INSERT, UPDATE, DELETE, etc. Read run_dql_query Run a raw DQL SQL query, like SELECT, SHOW, DESCRIBE, EXPLAIN, etc. Read get_columns Get all columns in a table. Read get_foreign_keys Get foreign keys in a table. Read get_indexes Get all indexes in a table. Read get_schema_names Get all schema names. Read get_tables Get all tables in a schema.

All 9 Pgsql tools →

Execute tools on other servers

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Go deeper

High-risk tools in Pgsql → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about run_dcl_query

What does the run_dcl_query tool do? +

Run a raw DCL SQL query, like GRANT, REVOKE, etc. It is categorised as a Execute tool in the Pgsql MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on run_dcl_query? +

Register the Pgsql MCP server in PolicyLayer and add a rule for run_dcl_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 Pgsql. Nothing to install.

What risk level is run_dcl_query? +

run_dcl_query is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit run_dcl_query? +

Yes. Add a rate_limit block to the run_dcl_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.

How do I block run_dcl_query completely? +

Set action: deny in the PolicyLayer policy for run_dcl_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.

What MCP server provides run_dcl_query? +

run_dcl_query is provided by the Pgsql MCP server (twn39/pgsql-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Pgsql tool call.

Start from Pgsql, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →