pg_jsonb_set

Set value in JSONB at path. Uses dot-notation by default; for literal dots in keys use array format [\

SERVERPostgreSQL MCP Server SOURCE@neverinfamous/postgres-mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-neverinfamous-postgres-mcp/pg-jsonb-set.md

WHAT IT DOES

What pg_jsonb_set does on PostgreSQL MCP Server

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

RISK

Why pg_jsonb_set is rated Medium

This tool modifies existing data by setting values in JSONB columns. While reversible (the previous value can be overwritten), it changes stored data and constitutes a Write operation. Severity is medium because JSONB modifications can affect application logic and data integrity, but the operation is not destructive (data is not deleted) and not irreversible in principle.

From the tool's definition Tool name and description indicate 'Set value in JSONB at path' — a direct data modification operation that creates or alters JSONB column data.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs pg_jsonb_set safely

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

pg_jsonb_set Rate-limited

pg_jsonb_set 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": {
    "pg_jsonb_set": {
      "limits": [
        {
          "counter": "pg_jsonb_set_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 PostgreSQL MCP Server, apply this rule, and every pg_jsonb_set call is checked against it from then on.

FAQ

Questions about pg_jsonb_set

What does the pg_jsonb_set tool do? +

Set value in JSONB at path. Uses dot-notation by default; for literal dots in keys use array format [\. It is categorised as a Write tool in the PostgreSQL MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on pg_jsonb_set? +

Register the PostgreSQL MCP Server MCP server in PolicyLayer and add a rule for pg_jsonb_set: 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 PostgreSQL MCP Server. Nothing to install.

What risk level is pg_jsonb_set? +

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

Can I rate-limit pg_jsonb_set? +

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

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

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

KEEP EXPLORING

What pg_jsonb_set does on PostgreSQL MCP Server

Why pg_jsonb_set is rated Medium

The rule that runs pg_jsonb_set safely

Questions about pg_jsonb_set

More on PostgreSQL MCP Server, and thousands of servers like it.