list_objects

Lists the names of objects in a Google Cloud Storage (GCS) bucket. Supports filtering by prefix, directory-like listing with a delimiter, pagination, and listing object versions.

Server Observability @google-cloud/observability-mcp
Category Read
Risk class Low
Parameters 00 required

What list_objects does on Observability

AI agents call list_objects to retrieve information from Observability without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

Why list_objects needs a policy

This tool only retrieves and queries metadata about objects in GCS without performing any side effects. It allows inspection of bucket contents but cannot create, modify, delete, or execute any operations on those objects. The capability to list versions is still a read operation.

From the tool's definition Tool description states it 'Lists the names of objects in a Google Cloud Storage (GCS) bucket' with support for 'filtering by prefix, directory-like listing with a delimiter, pagination, and listing object versions.' These are all read-only query operations…

Questions about list_objects

What does the list_objects tool do? +

Lists the names of objects in a Google Cloud Storage (GCS) bucket. Supports filtering by prefix, directory-like listing with a delimiter, pagination, and listing object versions. It is categorised as a Read tool in the Observability MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_objects? +

Register the Observability MCP server in PolicyLayer and add a rule for list_objects: 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 Observability. Nothing to install.

What risk level is list_objects? +

list_objects is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit list_objects? +

Yes. Add a rate_limit block to the list_objects 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.

How do I block list_objects completely? +

Set action: deny in the PolicyLayer policy for list_objects. 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.

What MCP server provides list_objects? +

list_objects is provided by the Observability MCP server (@google-cloud/observability-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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