Unshare a tool from a user (removes from their sharedTools array)
AI agents use unshare-tool to create or update resources in Dynamic MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Dynamic MCP Server environment.
This is a Write operation because it updates user data (the sharedTools array) in a reversible manner. While it restricts access to tools, it does not delete the tool itself, does not execute code, and does not move money. The severity is medium because misuse could deny legitimate users access to critical tools, but the operation is reversible (the tool can be reshared).
From the tool's definition Tool description states it 'Unshare a tool from a user (removes from their sharedTools array)' — this modifies a user's sharedTools array by removing an entry, which is a reversible data modification operation.
Documented attack patterns abuse exactly the kind of access unshare-tool gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Dynamic MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for unshare-tool:
{
"version": "1",
"default": "deny",
"tools": {
"unshare-tool": {
"limits": [
{
"counter": "unshare-tool_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}unshare-tool 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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Unshare a tool from a user (removes from their sharedTools array). It is categorised as a Write tool in the Dynamic MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Dynamic MCP Server MCP server in PolicyLayer and add a rule for unshare-tool: 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 Dynamic MCP Server. Nothing to install.
unshare-tool 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 unshare-tool 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 unshare-tool. 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.
unshare-tool is provided by the Dynamic MCP Server MCP server (scitara-cto/dynamic-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Dynamic MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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18 Dynamic MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.