AI agents call get_blob_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.
This tool retrieves metadata (a public URL) from an existing blob without side effects. It performs a read-only query operation. The severity is low because obtaining a public URL does not directly expose sensitive data (public URLs are by definition publicly accessible) and causes no modifications or destructive actions.
From the tool's definition Tool name 'get_blob_url' and description 'Get the public URL of a blob' indicate a retrieval operation that returns an existing URL without modifying or deleting data.
Documented attack patterns abuse exactly the kind of access get_blob_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 get_blob_url:
{
"version": "1",
"default": "deny",
"tools": {
"get_blob_url": {}
}
}get_blob_url is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get the public URL of a blob. 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 get_blob_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.
get_blob_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 get_blob_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 get_blob_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.
get_blob_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.
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23 Gcp Storage tools catalogued and risk-classified — across an index of 43,000+ MCP servers.