set_role

Set active PostgreSQL role/user for the session (SET ROLE) or reset to default (RESET ROLE)

SERVERPostgres SOURCE@allensandiego/postgres-mcp-server

Medium RISK CLASS

Category Write

Parameters 11 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/allensandiego-postgres-mcp-server/set-role.md

WHAT IT DOES

What set_role does on Postgres

AI agents use set_role to create or update resources in Postgres, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Postgres environment.

Parameter	Type	Required	Description
`role`	string	Yes	Role or username to set (e.g. 'analyst', 'app_user', or 'NONE' / 'RESET' to restore default)

Parameters from the server's own tool schema.

RISK

Why set_role is rated Medium

An AI agent can call set_role faster than any human can review: one bad instruction and it creates or modifies resources in Postgres by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs set_role safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Postgres, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For set_role, this is the rule to start with:

set_role Rate-limited

set_role stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_role": {
      "limits": [
        {
          "counter": "set_role_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Postgres, apply this rule, and every set_role call is checked against it from then on.

FAQ

Questions about set_role

What does the set_role tool do? +

Set active PostgreSQL role/user for the session (SET ROLE) or reset to default (RESET ROLE). It is categorised as a Write tool in the Postgres MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does set_role accept? +

set_role accepts 1 parameter: role. Required: role. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on set_role? +

Register the Postgres MCP server in PolicyLayer and add a rule for set_role: 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 Postgres. Nothing to install.

What risk level is set_role? +

set_role is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_role? +

Yes. Add a rate_limit block to the set_role 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 set_role completely? +

Set action: deny in the PolicyLayer policy for set_role. 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 set_role? +

set_role is provided by the Postgres MCP server (@allensandiego/postgres-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

What set_role does on Postgres

Why set_role is rated Medium

The rule that runs set_role safely

Questions about set_role

More on Postgres, and thousands of servers like it.