pg_jsonb_path_query
Query JSONB using SQL/JSON path expressions (PostgreSQL 12+). Note: Recursive descent (..) syntax is not supported by PostgreSQL.
This record as markdown: /tools/io-github-neverinfamous-postgres-mcp/pg-jsonb-path-query.md
What pg_jsonb_path_query does on PostgreSQL MCP Server
AI agents call pg_jsonb_path_query to retrieve information from PostgreSQL MCP Server without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why pg_jsonb_path_query is rated Low
This tool queries JSONB data structures using PostgreSQL's SQL/JSON path syntax. It retrieves information without altering, deleting, or executing code. The operation is read-only with no side effects, fitting the 'Read' category. Severity is low because query operations on data have minimal blast radius compared to write, execute, or destructive operations.
From the tool's definition Tool name 'pg_jsonb_path_query' and description 'Query JSONB using SQL/JSON path expressions' indicate a retrieval operation. The verb 'Query' combined with the absence of any modification, deletion, or execution language confirms read-only semantics.
Attacks that exploit this kind of access
The rule that runs pg_jsonb_path_query 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_path_query, this is the rule to start with:
pg_jsonb_path_query is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect PostgreSQL MCP Server, apply this rule, and every pg_jsonb_path_query call is checked against it from then on.
Questions about pg_jsonb_path_query
Query JSONB using SQL/JSON path expressions (PostgreSQL 12+). Note: Recursive descent (..) syntax is not supported by PostgreSQL. It is categorised as a Read tool in the PostgreSQL MCP Server MCP Server, which means it retrieves data without modifying state.
Register the PostgreSQL MCP Server MCP server in PolicyLayer and add a rule for pg_jsonb_path_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 PostgreSQL MCP Server. Nothing to install.
pg_jsonb_path_query is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the pg_jsonb_path_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 pg_jsonb_path_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.
pg_jsonb_path_query 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.
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