get_foreign_keys

THE RISK

Low Risk

Why get_foreign_keys needs a policy

This tool retrieves metadata about foreign key constraints in a table. It performs a read-only operation to inspect database schema structure. No data is created, modified, deleted, or destroyed. No code is executed. The operation has no side effects beyond returning information already present in the database catalog.

From the tool's definition Tool name 'get_foreign_keys' and description 'Get foreign keys in a table' indicate data retrieval with no modification. Grouped with other schema inspection tools (get_columns, get_indexes, get_schema_names, get_tables) that are non-destructive queries.

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

POLICY

How to control get_foreign_keys

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 get_foreign_keys:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "get_foreign_keys": {}
  }
}

get_foreign_keys is read-only, so it stays allowed — but 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.

CAP 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. Execute run_dcl_query Run a raw DCL SQL query, like GRANT, REVOKE, 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_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 →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about get_foreign_keys

What does the get_foreign_keys tool do? +

Get foreign keys in a table. It is categorised as a Read tool in the Pgsql MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on get_foreign_keys? +

Register the Pgsql MCP server in PolicyLayer and add a rule for get_foreign_keys: 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 get_foreign_keys? +

get_foreign_keys is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit get_foreign_keys? +

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

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

get_foreign_keys 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 →