govuk_lookup_postcode
AI agents call govuk_lookup_postcode to retrieve information from GOV UK Search without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Postcode lookup retrieves public UK government data and returns information without side effects. No data is created, modified, deleted, or executed. This is a straightforward data retrieval operation. Severity is low because postcode information is public and non-sensitive. Confidence is high despite empty tool description because the name and server context clearly indicate a read-only lookup operation.
From the tool's definition Tool name 'govuk_lookup_postcode' indicates postcode resolution/lookup. Server description states 'postcode resolution' as a capability. The tool performs a lookup operation (Read category) with no modification or destructive capability.
Attacks that exploit this kind of access
govuk_lookup_postcode. It is categorised as a Read tool in the GOV UK Search MCP Server, which means it retrieves data without modifying state.
Register the GOV UK Search MCP server in PolicyLayer and add a rule for govuk_lookup_postcode: 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 GOV UK Search. Nothing to install.
govuk_lookup_postcode 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 govuk_lookup_postcode 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 govuk_lookup_postcode. 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.
govuk_lookup_postcode is provided by the GOV UK Search MCP server (paulieb89/govuk-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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