AI agents call get-element-siblings to retrieve information from Mcp Dev without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns data about element relationships (sibling elements) based on an ID parameter. The verb 'Gets' and the retrieval pattern confirm this is a Read operation. There is no data creation, modification, deletion, or external execution involved. The blast radius of misuse is minimal—an attacker could only discover structural information about the CMS hierarchy.
From the tool's definition Tool name 'get-element-siblings' and description 'Gets sibling elements for a given descendant id' indicate a retrieval operation with no modification or side effects.
Attacks that exploit this kind of access
Gets sibling elements for a given descendant id. It is categorised as a Read tool in the Mcp Dev MCP Server, which means it retrieves data without modifying state.
Register the Mcp Dev MCP server in PolicyLayer and add a rule for get-element-siblings: 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 Mcp Dev. Nothing to install.
get-element-siblings 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 get-element-siblings 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 get-element-siblings. 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.
get-element-siblings is provided by the Mcp Dev MCP server (@umbraco-cms/mcp-dev). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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