AI agents call list_packages to retrieve information from Pharo Smalltalk Interop without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool appears to retrieve or enumerate packages from the Pharo Smalltalk image without side effects. The naming convention and context of similar read-only tools on the server make this a Read category with low severity—misuse would at worst leak metadata about available packages, not compromise data or execution.
From the tool's definition Tool name 'list_packages' indicates a retrieval operation. The lack of description is a limitation, but the name strongly suggests listing/querying packages without modification.
Documented attack patterns abuse exactly the kind of access list_packages gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Pharo Smalltalk Interop, and nothing reaches the server without passing your rules. This is the rule we recommend for list_packages:
{
"version": "1",
"default": "deny",
"tools": {
"list_packages": {}
}
}list_packages is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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list_packages. It is categorised as a Read tool in the Pharo Smalltalk Interop MCP Server, which means it retrieves data without modifying state.
Register the Pharo Smalltalk Interop MCP server in PolicyLayer and add a rule for list_packages: 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 Pharo Smalltalk Interop. Nothing to install.
list_packages 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 list_packages 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 list_packages. 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.
list_packages is provided by the Pharo Smalltalk Interop MCP server (mumez/pharo-smalltalk-interop-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Pharo Smalltalk Interop, 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 Pharo Smalltalk Interop tools catalogued and risk-classified — across an index of 43,000+ MCP servers.