Preview a SQL file without executing it. Shows statement count, types breakdown, and warnings for potentially dangerous operations (DROP, TRUNCATE, DELETE/UPDATE without WHERE). Similar to mutation_preview but for SQL files. Use this before execute_sql_file to understand what a migration will do.
AI agents call preview_sql_file to retrieve information from Postgres without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only reads and analyzes a SQL file's contents — it does not execute any statements. It surfaces metadata (statement count, type breakdown, warnings) to help users understand a migration before running it. No data is modified or executed, making it a Read-category tool with low severity.
From the tool's definition Preview a SQL file without executing it. Shows statement count, types breakdown, and warnings for potentially dangerous operations.
Attacks that exploit this kind of access
Preview a SQL file without executing it. Shows statement count, types breakdown, and warnings for potentially dangerous operations (DROP, TRUNCATE, DELETE/UPDATE without WHERE). Similar to mutation_preview but for SQL files. Use this before execute_sql_file to understand what a migration will do. It is categorised as a Read tool in the Postgres MCP Server, which means it retrieves data without modifying state.
Register the Postgres MCP server in PolicyLayer and add a rule for preview_sql_file: 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 Postgres. Nothing to install.
preview_sql_file is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the preview_sql_file 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 preview_sql_file. 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.
preview_sql_file is provided by the Postgres MCP server (teja-sudo/postgres-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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