Discover columns in a specific table by querying it
AI agents call supabase_discover_columns 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 performs a read-only operation that queries database schema information. It retrieves column definitions and metadata for a specified table, which is a passive discovery operation with no side effects, data modification, or external execution. This aligns with the 'Read' category for data retrieval operations.
From the tool's definition Tool name 'discover_columns' and description 'Discover columns in a specific table by querying it' indicate schema introspection—retrieving metadata about table structure without modifying data.
Attacks that exploit this kind of access
Discover columns in a specific table by querying it. 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_columns: 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_columns 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_columns 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_columns. 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_columns 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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