AI agents call search_by_word_count to retrieve information from Obsidian MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries the vault to locate notes matching a word count criterion. It performs a search without modifying, executing, or deleting any data. Word count filtering is a read-only retrieval operation that poses minimal security risk even if misused by an AI agent—the worst outcome would be retrieving an unintended set of notes.
From the tool's definition Tool name 'search_by_word_count' and description 'Find notes by word count range' indicate a query/retrieval operation. The verb 'Find' and action of searching by a metric (word count) constitute data retrieval with no side effects.
Documented attack patterns abuse exactly the kind of access search_by_word_count gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Obsidian MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for search_by_word_count:
{
"version": "1",
"default": "deny",
"tools": {
"search_by_word_count": {}
}
}search_by_word_count is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Find notes by word count range. It is categorised as a Read tool in the Obsidian MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Obsidian MCP Server MCP server in PolicyLayer and add a rule for search_by_word_count: 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 Obsidian MCP Server. Nothing to install.
search_by_word_count 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_by_word_count 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_by_word_count. 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_by_word_count is provided by the Obsidian MCP Server MCP server (kynlos/obsidian-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Obsidian MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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120 Obsidian MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.