Discover database schema via PostgREST OpenAPI endpoint
AI agents call supabase_discover_openapi to retrieve information from Supabase MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries the OpenAPI specification to inspect database structure (tables, columns, types). It is a read-only discovery operation with no side effects on data or system state. Severity is low because schema information alone poses minimal risk; the actual data access and modification operations are handled by sibling tools like supabase_delete, supabase_create_user, etc.
From the tool's definition Tool name includes 'discover' and description states 'Discover database schema via PostgREST OpenAPI endpoint' — retrieves schema metadata without modification.
Attacks that exploit this kind of access
Discover database schema via PostgREST OpenAPI endpoint. It is categorised as a Read tool in the Supabase MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Supabase MCP Server MCP server in PolicyLayer and add a rule for supabase_discover_openapi: 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 Supabase MCP Server. Nothing to install.
supabase_discover_openapi 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 supabase_discover_openapi 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 supabase_discover_openapi. 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.
supabase_discover_openapi is provided by the Supabase MCP Server MCP server (sweir1/supabase-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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