AI agents call xbrl_peer_comparison to retrieve information from Arelle without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Despite the empty description creating some ambiguity, the naming convention and context (peer comparison in XBRL/financial analysis) strongly indicate this retrieves and compares financial data from filings. No modification, deletion, execution, or financial transaction is implied. The medium severity reflects that financial data exposure could inform decisions, but the tool itself performs read-only analysis.
From the tool's definition Tool name 'xbrl_peer_comparison' suggests comparing XBRL filings between peer companies. The server description indicates this MCP enables analysis of financial filings; peer comparison would retrieve and query comparative financial data without modifying it.
Attacks that exploit this kind of access
xbrl_peer_comparison. It is categorised as a Read tool in the Arelle MCP Server, which means it retrieves data without modifying state.
Register the Arelle MCP server in PolicyLayer and add a rule for xbrl_peer_comparison: 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 Arelle. Nothing to install.
xbrl_peer_comparison 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 xbrl_peer_comparison 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 xbrl_peer_comparison. 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.
xbrl_peer_comparison is provided by the Arelle MCP server (thekinghippopotamus/arelle-mcp). 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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