Create a new highlight in your Readwise library
Part of the Readwise server.
Free to start. No card required.
AI agents use create_highlight to create or modify resources in Readwise. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call create_highlight repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Readwise.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"create_highlight": {
"limits": [
{
"counter": "create_highlight_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Readwise policy for all 30 tools.
These attack patterns abuse exactly the kind of access create_highlight gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Create a new highlight in your Readwise library. It is categorised as a Write tool in the Readwise MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Readwise MCP server in PolicyLayer and add a rule for create_highlight: 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. Nothing to install.
create_highlight is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the create_highlight 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 create_highlight. 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.
create_highlight is provided by the Readwise MCP server (IAmAlexander/readwise-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 30 Readwise tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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