# filter_instances

Filter EC2 instances based on specified criteria.

Agent View of the PolicyLayer registry record for `filter_instances`. HTML page: https://policylayer.com/tools/aadarshjain-postgres-mcp-server/filter-instances

## Facts

- Tool: `filter_instances`
- Server: PostgreSQL MCP Server (`aadarshjain/postgres-mcp-server`) — https://policylayer.com/tools/aadarshjain-postgres-mcp-server.md
- Homepage: https://github.com/aadarshjain/postgres-mcp-server
- 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": "filter_instances",
    "arguments": {}
  }
}
```

## Why filter_instances is rated Low

The tool performs filtering and retrieval of EC2 instance information—a read-only operation with no side effects. Filtering is a standard data retrieval operation analogous to the 'list' and 'get' operations mentioned in the server description. No code execution, data modification, deletion, or financial transactions are implied. The low severity reflects minimal blast radius if misused by an AI agent.

From the tool's own definition: "Tool name 'filter_instances' and description 'Filter EC2 instances based on specified criteria' indicate a query/search operation that retrieves instance metadata without modifying, deleting, or executing actions on those instances."

## Use case

AI agents call filter_instances 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": {
    "filter_instances": {}
  }
}
```

## Other tools on PostgreSQL MCP Server (4)

- `execute_query` — Execute — https://policylayer.com/tools/aadarshjain-postgres-mcp-server/execute-query.md
- `get_database_stats` — Read — https://policylayer.com/tools/aadarshjain-postgres-mcp-server/get-database-stats.md
- `get_table_schema` — Read — https://policylayer.com/tools/aadarshjain-postgres-mcp-server/get-table-schema.md
- `list_tables` — Read — https://policylayer.com/tools/aadarshjain-postgres-mcp-server/list-tables.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=aadarshjain-postgres-mcp-server · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/aadarshjain-postgres-mcp-server