# list_constraints

A read tool on the Mcpg MCP server.

Agent View of the PolicyLayer registry record for `list_constraints`. HTML page: https://policylayer.com/tools/io-github-devopam-mcpg/list-constraints

## Facts

- Tool: `list_constraints`
- Server: Mcpg (`pypi:mcpg`) — https://policylayer.com/tools/io-github-devopam-mcpg.md
- Install: `npx -y pypi:mcpg`
- Homepage: https://github.com/devopam/MCPg
- Risk category: Read (Low risk)
- Registry record: grade F, 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_constraints",
    "arguments": {}
  }
}
```

## Why list_constraints is rated Low

The tool lists database constraints, which is a non-destructive query operation that retrieves schema metadata. It has no side effects and cannot modify, delete, or execute operations. The empty description lowers confidence slightly, but the naming convention strongly suggests a simple schema inspection tool.

From the tool's own definition: "Tool name 'list_constraints' indicates a retrieval operation that queries database metadata/schema information without modifying data. The 'list' prefix is characteristic of Read operations."

## Use case

AI agents call list_constraints to retrieve information from Mcpg 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 Mcpg:

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

## Other tools on Mcpg (251)

- `cancel_migration` — Destructive — https://policylayer.com/tools/io-github-devopam-mcpg/cancel-migration.md
- `drop_graph` — Destructive — https://policylayer.com/tools/io-github-devopam-mcpg/drop-graph.md
- `drop_property_graph` — Destructive — https://policylayer.com/tools/io-github-devopam-mcpg/drop-property-graph.md
- `drop_publication` — Destructive — https://policylayer.com/tools/io-github-devopam-mcpg/drop-publication.md
- `drop_subscription` — Destructive — https://policylayer.com/tools/io-github-devopam-mcpg/drop-subscription.md
- `dump_database` — Destructive — https://policylayer.com/tools/io-github-devopam-mcpg/dump-database.md
- `partman_drop_partition` — Destructive — https://policylayer.com/tools/io-github-devopam-mcpg/partman-drop-partition.md
- `prune_audit_events` — Destructive — https://policylayer.com/tools/io-github-devopam-mcpg/prune-audit-events.md
- `restore_database` — Destructive — https://policylayer.com/tools/io-github-devopam-mcpg/restore-database.md
- `cancel_query` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/cancel-query.md
- `cluster_vectors` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/cluster-vectors.md
- `complete_migration` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/complete-migration.md
- `dry_run_ddl` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/dry-run-ddl.md
- `enable_extension` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/enable-extension.md
- `enable_logical_replication_on_demand` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/enable-logical-replication-on-demand.md
- `enable_redis_fdw` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/enable-redis-fdw.md
- `generate_graph_projection` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/generate-graph-projection.md
- `generate_test_data` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/generate-test-data.md
- `hybrid_search` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/hybrid-search.md
- `maintain_turboquant_index` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/maintain-turboquant-index.md
- `mmr_search` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/mmr-search.md
- `open_cursor` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/open-cursor.md
- `optimize_query` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/optimize-query.md
- `partman_run_maintenance` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/partman-run-maintenance.md
- `pg_search_run` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/pg-search-run.md
- `prepare_migration` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/prepare-migration.md
- `prewarm_recommended` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/prewarm-recommended.md
- `prewarm_relation` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/prewarm-relation.md
- `recommend_redistribute` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/recommend-redistribute.md
- `reindex_pg_search_index` — Execute — https://policylayer.com/tools/io-github-devopam-mcpg/reindex-pg-search-index.md
- …and 221 more: https://policylayer.com/tools/io-github-devopam-mcpg.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=io-github-devopam-mcpg · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-devopam-mcpg