ngram_frequencies
AI agents call ngram_frequencies to retrieve information from DHLAB MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
N-gram frequency analysis retrieves statistical information from a corpus without modifying, deleting, or executing arbitrary code. It is a read-only analytical operation. Confidence is slightly reduced due to the empty description, but the server's clear read-only purpose and consistent sibling tools strongly indicate this is a data retrieval function.
From the tool's definition Tool name 'ngram_frequencies' indicates frequency analysis of n-grams (word sequences). Server context shows this is a National Library digital humanities search tool providing 'NGram analysis' alongside other read-only operations like search_texts,…
Attacks that exploit this kind of access
ngram_frequencies. It is categorised as a Read tool in the DHLAB MCP Server MCP Server, which means it retrieves data without modifying state.
Register the DHLAB MCP Server MCP server in PolicyLayer and add a rule for ngram_frequencies: 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 DHLAB MCP Server. Nothing to install.
ngram_frequencies 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 ngram_frequencies 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 ngram_frequencies. 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.
ngram_frequencies is provided by the DHLAB MCP Server MCP server (marksverdhei/dhlab-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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