AI agents use write_object_safe to create or update resources in Storage — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Storage environment.
This tool creates new objects in cloud storage, which is a write operation. The safety constraint (failing if object exists) prevents accidental overwrites, reducing severity from high to medium. However, an agent could still fill storage quotas, create malicious files, or store sensitive data. It is reversible (unlike Destructive), does not execute code (unlike Execute), and involves no financial impact.
From the tool's definition Tool name and description: 'Writes a new object to the bucket. Fails if the object already exists.' The 'safe' suffix and failure condition on existing objects indicate this is a reversible create operation without overwrite capability.
Attacks that exploit this kind of access
Writes a new object to the bucket. Fails if the object already exists. It is categorised as a Write tool in the Storage MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Storage MCP server in PolicyLayer and add a rule for write_object_safe: 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 Storage. Nothing to install.
write_object_safe is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the write_object_safe 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 write_object_safe. 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.
write_object_safe is provided by the Storage MCP server (@google-cloud/storage-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.