Show specific changes in a file between branches
AI agents call show_file_diff to retrieve information from Simple Merge Review MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries git diff information to display file changes between branches. It has no write, execute, or destructive side effects; it only retrieves and presents data. The server description emphasizes 'lightweight Git merge analysis' with 'quick overviews,' confirming a read-only intent. Severity is low because viewing diffs poses minimal risk even if misused by an AI agent.
From the tool's definition The tool 'show_file_diff' is described as showing 'specific changes in a file between branches' — a read-only operation that retrieves and displays differences without modifying data.
Attacks that exploit this kind of access
Show specific changes in a file between branches. It is categorised as a Read tool in the Simple Merge Review MCP MCP Server, which means it retrieves data without modifying state.
Register the Simple Merge Review MCP server in PolicyLayer and add a rule for show_file_diff: 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 Simple Merge Review MCP. Nothing to install.
show_file_diff 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 show_file_diff 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 show_file_diff. 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.
show_file_diff is provided by the Simple Merge Review MCP server (sigmade/git-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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