# mysql_add_foreign_key

A write tool on the Mysql MCP server.

Agent View of the PolicyLayer registry record for `mysql_add_foreign_key`. HTML page: https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-add-foreign-key

## Facts

- Tool: `mysql_add_foreign_key`
- Server: Mysql (`mukul975/mysql-mcp-server`) — https://policylayer.com/tools/mukul975-mysql-mcp-server.md
- Homepage: https://github.com/mukul975/mysql-mcp-server
- Risk category: Write (Medium risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

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

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

## Why mysql_add_foreign_key is rated Medium

Adding a foreign key constraint is a reversible schema modification (Write category) rather than Destructive because the constraint can be dropped. However, the severity is high because altering database schema can impact application behavior, data integrity enforcement, and requires administrative privileges.

From the tool's own definition: "Tool name 'mysql_add_foreign_key' indicates modification of database schema by adding a foreign key constraint. Server description claims 'read-only queries' but this tool modifies schema structure, contradicting that claim."

## Use case

AI agents use mysql_add_foreign_key to create or update resources in Mysql, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mysql environment.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Mysql:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "mysql_add_foreign_key": {
      "limits": [
        {
          "counter": "mysql_add_foreign_key_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Mysql (232)

- `drop_event` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/drop-event.md
- `drop_partition` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/drop-partition.md
- `drop_role` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/drop-role.md
- `drop_stored_function` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/drop-stored-function.md
- `drop_stored_procedure` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/drop-stored-procedure.md
- `mysql_alter_table_drop_column` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-alter-table-drop-column.md
- `mysql_delete_data` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-delete-data.md
- `mysql_drop_database` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-drop-database.md
- `mysql_drop_foreign_key` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-drop-foreign-key.md
- `mysql_drop_index` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-drop-index.md
- `mysql_drop_primary_key` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-drop-primary-key.md
- `mysql_drop_table` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-drop-table.md
- `mysql_drop_user` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-drop-user.md
- `mysql_drop_view` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-drop-view.md
- `mysql_kill_process` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-kill-process.md
- `mysql_reset_query_cache` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-reset-query-cache.md
- `mysql_revoke_privileges` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-revoke-privileges.md
- `mysql_truncate_table` — Destructive — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-truncate-table.md
- `create_event` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/create-event.md
- `create_stored_procedure` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/create-stored-procedure.md
- `mysql_analyze_table` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-analyze-table.md
- `mysql_auto_index_rebuild_scheduler` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-auto-index-rebuild-scheduler.md
- `mysql_flush_logs` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-flush-logs.md
- `mysql_flush_privileges` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-flush-privileges.md
- `mysql_flush_tables` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-flush-tables.md
- `mysql_lock_tables` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-lock-tables.md
- `mysql_optimize_table` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-optimize-table.md
- `mysql_repair_table` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-repair-table.md
- `mysql_set_variable` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-set-variable.md
- `mysql_unlock_tables` — Execute — https://policylayer.com/tools/mukul975-mysql-mcp-server/mysql-unlock-tables.md
- …and 202 more: https://policylayer.com/tools/mukul975-mysql-mcp-server.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`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=mukul975-mysql-mcp-server · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/mukul975-mysql-mcp-server