Search academic papers from CrossRef database. CrossRef is a scholarly infrastructure organization that provides persistent identifiers (DOIs) for scholarly content and metadata. It's one of the largest citation databases covering millions of academic papers, journals, books, and other scholarly ...
AI agents call search_crossref to retrieve information from Paper Search MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a straightforward read operation that queries and retrieves academic paper metadata from a public database. The tool has no side effects, cannot modify data, and poses minimal risk even if misused by an AI agent (worst case: excessive queries to a public API).
From the tool's definition Tool performs 'Search academic papers from CrossRef database' with arguments for query, max_results, and filter. The description explicitly states it searches and retrieves metadata from the CrossRef database—a scholarly citation database.
Documented attack patterns abuse exactly the kind of access search_crossref gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Paper Search MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for search_crossref:
{
"version": "1",
"default": "deny",
"tools": {
"search_crossref": {}
}
}search_crossref is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Search academic papers from CrossRef database. CrossRef is a scholarly infrastructure organization that provides persistent identifiers (DOIs) for scholarly content and metadata. It's one of the largest citation databases covering millions of academic papers, journals, books, and other scholarly content. Args: query: Search query string (e.g., 'machine learning', 'climate change'). max_results: Maximum number of papers to return (default: 10, max: 1000). filter: CrossRef filter string (e.g., 'has-full-text:true,from-pub-date:2020'). sort: Sort field ('relevance', 'published', 'updated', 'deposited', etc.). order: Sort order ('asc' or 'desc'). Returns: List of paper metadata in dictionary format. It is categorised as a Read tool in the Paper Search MCP MCP Server, which means it retrieves data without modifying state.
Register the Paper Search MCP server in PolicyLayer and add a rule for search_crossref: 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 Paper Search MCP. Nothing to install.
search_crossref 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 search_crossref 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 search_crossref. 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.
search_crossref is provided by the Paper Search MCP server (openags/paper-search-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 63 Paper Search MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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63 Paper Search MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.