Show changes between branches before merge
AI agents call show_merge_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 retrieves and displays differences between Git branches for review purposes. It has no side effects, does not modify repositories, and does not execute code or trigger external operations. It is purely informational, making it a Read operation with low severity risk.
From the tool's definition Tool name 'show_merge_diff' and description 'Show changes between branches before merge' indicate retrieval and display of diff information. The server description emphasizes 'quick overviews of changes' and 'analysis' without modification capabilities.
Attacks that exploit this kind of access
Show changes between branches before merge. 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_merge_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_merge_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_merge_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_merge_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_merge_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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