AI agents call enrich_dois to retrieve information from Crossref Local without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool appears to retrieve or enrich Digital Object Identifiers (DOIs) with additional metadata from the CrossRef database. This is a read operation that queries and returns data without side effects. The empty description lowers confidence slightly, but the naming convention and sibling tool patterns (all read/cache operations) strongly suggest this retrieves rather than modifies data.
From the tool's definition Tool name 'enrich_dois' combined with server context of CrossRef database operations. Related sibling tools like 'cache_citation_summary', 'cache_query', and 'cache_stats' are all read operations that retrieve scholarly metadata.
Documented attack patterns abuse exactly the kind of access enrich_dois gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Crossref Local, and nothing reaches the server without passing your rules. This is the rule we recommend for enrich_dois:
{
"version": "1",
"default": "deny",
"tools": {
"enrich_dois": {}
}
}enrich_dois is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
enrich_dois. It is categorised as a Read tool in the Crossref Local MCP Server, which means it retrieves data without modifying state.
Register the Crossref Local MCP server in PolicyLayer and add a rule for enrich_dois: 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 Crossref Local. Nothing to install.
enrich_dois 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 enrich_dois 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 enrich_dois. 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.
enrich_dois is provided by the Crossref Local MCP server (ywatanabe1989/crossref-local). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Crossref Local, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
17 Crossref Local tools catalogued and risk-classified — across an index of 43,000+ MCP servers.