Get signed URL for Supabase Storage object
AI agents call supabase.storage_get_signed_url to retrieve information from MCP Fullstack without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves a signed URL, which is a read operation that queries Supabase Storage to obtain access credentials. While the tool itself performs no side effects and doesn't modify or delete data, signed URLs grant access to potentially sensitive objects.
From the tool's definition Tool name contains 'get' and description states 'Get signed URL for Supabase Storage object' - retrieves a URL without modifying or deleting data. However, the signed URL could potentially be used to access sensitive data stored in Supabase Storage.
Attacks that exploit this kind of access
Get signed URL for Supabase Storage object. It is categorised as a Read tool in the MCP Fullstack MCP Server, which means it retrieves data without modifying state.
Register the MCP Fullstack MCP server in PolicyLayer and add a rule for supabase.storage_get_signed_url: 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 MCP Fullstack. Nothing to install.
supabase.storage_get_signed_url 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.storage_get_signed_url 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.storage_get_signed_url. 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.storage_get_signed_url is provided by the MCP Fullstack MCP server (jacobfv/mcp-fullstack). 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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