Validate JSONPath expression with security checks
AI agents call json_validate_path to retrieve information from Postgres Mcp Legacy without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool reads and validates JSONPath expressions as input, performing static analysis or checks against them. It has no side effects on data—it does not modify, delete, or execute external operations. The 'security checks' mentioned are defensive validation measures, not operations that execute code or trigger external effects.
From the tool's definition The tool name 'json_validate_path' combined with description 'Validate JSONPath expression with security checks' indicates a validation/verification function that analyzes JSON path expressions.
Documented attack patterns abuse exactly the kind of access json_validate_path gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Postgres Mcp Legacy, and nothing reaches the server without passing your rules. This is the rule we recommend for json_validate_path:
{
"version": "1",
"default": "deny",
"tools": {
"json_validate_path": {}
}
}json_validate_path is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Validate JSONPath expression with security checks. It is categorised as a Read tool in the Postgres Mcp Legacy MCP Server, which means it retrieves data without modifying state.
Register the Postgres Mcp Legacy MCP server in PolicyLayer and add a rule for json_validate_path: 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 Mcp Legacy. Nothing to install.
json_validate_path 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 json_validate_path 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 json_validate_path. 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.
json_validate_path is provided by the Postgres Mcp Legacy MCP server (neverinfamous/postgres-mcp-legacy). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Postgres Mcp Legacy, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
60 Postgres Mcp Legacy tools catalogued and risk-classified — across an index of 43,000+ MCP servers.