AI agents call get_owned_books to retrieve information from Hardcover without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and displays existing data from the user's library without modifying, deleting, or executing any operations. It is a straightforward read-only query that lists owned books, fitting the 'Read' category for data retrieval operations.
From the tool's definition Tool name 'get_owned_books' and description 'List all books you have marked as owned' indicate a retrieval/query operation with no side effects.
Attacks that exploit this kind of access
List all books you have marked as owned. It is categorised as a Read tool in the Hardcover MCP Server, which means it retrieves data without modifying state.
Register the Hardcover MCP server in PolicyLayer and add a rule for get_owned_books: 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 Hardcover. Nothing to install.
get_owned_books 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_owned_books 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_owned_books. 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_owned_books is provided by the Hardcover MCP server (kristianedlund/hardcover-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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