Calculate OpenSubtitles hash for local movie files
AI agents call calculate_file_hash to retrieve information from OpenSubtitles MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only operation on local files to compute a hash value, similar to running a checksum utility. It retrieves/computes information from data (the local file) without side effects, reversible changes, code execution with external effects, or destructive operations. The hash is used to support subtitle searching but does not itself modify or delete anything.
From the tool's definition Tool calculates a hash value from a local movie file. The description states 'Calculate OpenSubtitles hash for local movie files' — this is a computational operation that reads file data to produce a hash digest.
Attacks that exploit this kind of access
Calculate OpenSubtitles hash for local movie files. It is categorised as a Read tool in the OpenSubtitles MCP Server MCP Server, which means it retrieves data without modifying state.
Register the OpenSubtitles MCP Server MCP server in PolicyLayer and add a rule for calculate_file_hash: 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 OpenSubtitles MCP Server. Nothing to install.
calculate_file_hash 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 calculate_file_hash 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 calculate_file_hash. 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.
calculate_file_hash is provided by the OpenSubtitles MCP Server MCP server (opensubtitles/mcp.opensubtitles.com). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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