AI agents call generate_signed_url to retrieve information from Gcp Storage without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Generating a signed URL is a read/metadata operation — it produces a time-limited URL granting access to a resource without modifying or deleting any data. However, signed URLs can grant third-party access to sensitive or private blobs, so misuse could expose data unintentionally, warranting medium severity. Confidence is reduced due to the empty description.
From the tool's definition Tool name 'generate_signed_url'; description is empty. Server description mentions 'generating signed URLs' as a supported operation.
Documented attack patterns abuse exactly the kind of access generate_signed_url gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Gcp Storage, and nothing reaches the server without passing your rules. This is the rule we recommend for generate_signed_url:
{
"version": "1",
"default": "deny",
"tools": {
"generate_signed_url": {}
}
}generate_signed_url is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
generate_signed_url. It is categorised as a Read tool in the Gcp Storage MCP Server, which means it retrieves data without modifying state.
Register the Gcp Storage MCP server in PolicyLayer and add a rule for generate_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 Gcp Storage. Nothing to install.
generate_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 generate_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 generate_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.
generate_signed_url is provided by the Gcp Storage MCP server (uysalserkan/gcp-storage-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Gcp Storage, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
23 Gcp Storage tools catalogued and risk-classified — across an index of 43,000+ MCP servers.