Applies a SQL migration to the database. SQL passed to this tool will be tracked within the database, so LLMs should use this for DDL operations (schema changes).
AI agents invoke apply_migration to trigger actions in PostgREST. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool executes arbitrary SQL migrations including DDL operations (schema changes) against a database. While it 'tracks' changes, it can include destructive operations like DROP TABLE or ALTER TABLE.
From the tool's definition Applies a SQL migration to the database. SQL passed to this tool will be tracked within the database, so LLMs should use this for DDL operations (schema changes).
Documented attack patterns abuse exactly the kind of access apply_migration gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and PostgREST, and nothing reaches the server without passing your rules. This is the rule we recommend for apply_migration:
{
"version": "1",
"default": "deny",
"tools": {
"apply_migration": {
"limits": [
{
"counter": "apply_migration_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}apply_migration stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Applies a SQL migration to the database. SQL passed to this tool will be tracked within the database, so LLMs should use this for DDL operations (schema changes). It is categorised as a Execute tool in the PostgREST MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the PostgREST MCP server in PolicyLayer and add a rule for apply_migration: 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 PostgREST. Nothing to install.
apply_migration is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the apply_migration 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.
Set action: deny in the PolicyLayer policy for apply_migration. 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.
apply_migration is provided by the PostgREST MCP server (supabase/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 32 PostgREST tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
32 PostgREST tools catalogued and risk-classified — across an index of 42,500+ MCP servers.