# list_schemas

List all schemas in the current database.

Agent View of the PolicyLayer registry record for `list_schemas`. HTML page: https://policylayer.com/tools/aeiyannn-postgree-mcp/list-schemas

## Facts

- Tool: `list_schemas`
- Server: PostgreSQL MCP Server (`aeiyannn/postgree-mcp`) — https://policylayer.com/tools/aeiyannn-postgree-mcp.md
- Homepage: https://github.com/aeiyannn/postgree-mcp
- Risk category: Read (Low risk)
- Registry record: grade C, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "list_schemas",
    "arguments": {}
  }
}
```

## Why list_schemas is rated Low

This tool queries database metadata to enumerate schemas. It performs read-only introspection with no ability to modify, delete, or execute operations. The blast radius of misuse is minimal; an agent listing schemas gathers information but cannot alter the database or trigger external effects. Severity is low because schema enumeration is a standard, safe administrative query.

From the tool's own definition: "Tool name is 'list_schemas' and description states 'List all schemas in the current database' — a retrieval operation with no side effects."

## Use case

AI agents call list_schemas 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.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches PostgreSQL MCP Server:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_schemas": {}
  }
}
```

## Other tools on PostgreSQL MCP Server (4)

- `execute` — Destructive — https://policylayer.com/tools/aeiyannn-postgree-mcp/execute.md
- `describe_table` — Read — https://policylayer.com/tools/aeiyannn-postgree-mcp/describe-table.md
- `list_tables` — Read — https://policylayer.com/tools/aeiyannn-postgree-mcp/list-tables.md
- `query` — Read — https://policylayer.com/tools/aeiyannn-postgree-mcp/query.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=aeiyannn-postgree-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/aeiyannn-postgree-mcp