Generate a presigned URL for object download
AI agents call minio_presigned_url to retrieve information from MinIO MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Generating a presigned URL is a read operation—it retrieves access credentials for downloading data but does not modify, create, delete, or execute any operations. The presigned URL itself is a temporary credential artifact, not a data-modifying action. Severity is low because presigned URLs have limited lifetime, are typically scoped to specific objects, and do not grant write or destructive capabilities.
From the tool's definition Tool name explicitly states 'presigned_url' and description specifies 'for object download'. Presigned URLs are read-only access tokens that enable temporary, delegated access to retrieve objects without modifying them.
Attacks that exploit this kind of access
Generate a presigned URL for object download. It is categorised as a Read tool in the MinIO MCP Server MCP Server, which means it retrieves data without modifying state.
Register the MinIO MCP Server MCP server in PolicyLayer and add a rule for minio_presigned_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 MinIO MCP Server. Nothing to install.
minio_presigned_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 minio_presigned_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 minio_presigned_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.
minio_presigned_url is provided by the MinIO MCP Server MCP server (raphaelren/minio-mcp). 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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