AI agents use import_package to create or update resources in Pharo Smalltalk Interop — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Pharo Smalltalk Interop environment.
Importing a package creates or adds code artifacts to the Smalltalk image, making it a Write operation (reversible modification of the system state). It is not Read (no data retrieval only), not Destructive (package imports are typically reversible), and not Execute in isolation (though the imported code could later be executed).
From the tool's definition Tool name is 'import_package' on a Pharo Smalltalk interop server. The sibling tools include 'export_package' and 'install_project', indicating this server manages code packages.
Documented attack patterns abuse exactly the kind of access import_package 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 import_package:
{
"version": "1",
"default": "deny",
"tools": {
"import_package": {
"limits": [
{
"counter": "import_package_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}import_package stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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import_package. It is categorised as a Write tool in the Pharo Smalltalk Interop MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Pharo Smalltalk Interop MCP server in PolicyLayer and add a rule for import_package: 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.
import_package 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 import_package 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 import_package. 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.
import_package 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.