Get highlights for a specific book
AI agents call readwise_book_highlights to retrieve information from Readwise MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only query to retrieve highlight data associated with a book. There are no side effects, no data modification, no execution of external operations, and no financial implications. The operation is purely informational retrieval from the Readwise service. Blast radius is minimal as misuse would only result in unauthorized information access within the user's own Readwise library.
From the tool's definition Tool name 'readwise_book_highlights' and description 'Get highlights for a specific book' both clearly indicate data retrieval with no modification or deletion. The verb 'Get' is explicitly retrieve-only.
Attacks that exploit this kind of access
Get highlights for a specific book. It is categorised as a Read tool in the Readwise MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Readwise MCP Server MCP server in PolicyLayer and add a rule for readwise_book_highlights: 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 Readwise MCP Server. Nothing to install.
readwise_book_highlights 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 readwise_book_highlights 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 readwise_book_highlights. 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.
readwise_book_highlights is provided by the Readwise MCP Server MCP server (ngpestelos/readwise-mcp-server). 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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