Get cross-references for a gene symbol
AI agents call get_xrefs_by_symbol to retrieve information from Ensembl MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves cross-reference information (likely mapping a gene symbol to external database identifiers) without creating, modifying, deleting, or executing any operations. It is purely a data lookup operation consistent with other Read category tools on the server (get_sequence, get_variants_for_region, etc.).
From the tool's definition Tool name 'get_xrefs_by_symbol' and description 'Get cross-references for a gene symbol' indicate a retrieval operation. The verb 'get' and the read-only nature of retrieving cross-reference data confirms this is a query with no side effects.
Attacks that exploit this kind of access
Get cross-references for a gene symbol. It is categorised as a Read tool in the Ensembl MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Ensembl MCP Server MCP server in PolicyLayer and add a rule for get_xrefs_by_symbol: 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 Ensembl MCP Server. Nothing to install.
get_xrefs_by_symbol 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_xrefs_by_symbol 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_xrefs_by_symbol. 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_xrefs_by_symbol is provided by the Ensembl MCP Server MCP server (munch-group/ensembl-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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