vcs_diff
Unified diff of the working tree (default) or the staged index (staged=true), optionally scoped to a single path (res:// or repo-relative). Returns the patch text (tail-truncated for large diffs) plus the list of changed files parsed from it. Read-only.
This record as markdown: /tools/breakpoint-mcp/vcs-diff.md
What vcs_diff does on Breakpoint
AI agents call vcs_diff to retrieve information from Breakpoint without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
path | string | — | Restrict the diff to this path (res:// or repo-relative) |
staged | boolean | — | Diff the staged index vs HEAD instead of the working tree (default false) |
Parameters from the server's own tool schema.
Why vcs_diff is rated Low
vcs_diff retrieves and queries version control information without modifying any data. It generates a diff output for inspection purposes only, making it a Read operation with low severity—an AI agent misusing it would at worst examine unintended code changes, but cannot make irreversible changes or execute arbitrary commands.
From the tool's definition Tool explicitly performs 'Unified diff of the working tree' and is marked 'Read-only'. Returns 'patch text' and 'list of changed files parsed from it' with no modification operations.
Risk signalsAccepts file system path (path)
Attacks that exploit this kind of access
The rule that runs vcs_diff safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Breakpoint, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For vcs_diff, this is the rule to start with:
vcs_diff is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Breakpoint, apply this rule, and every vcs_diff call is checked against it from then on.
Questions about vcs_diff
Unified diff of the working tree (default) or the staged index (staged=true), optionally scoped to a single path (res:// or repo-relative). Returns the patch text (tail-truncated for large diffs) plus the list of changed files parsed from it. Read-only. It is categorised as a Read tool in the Breakpoint MCP Server, which means it retrieves data without modifying state.
vcs_diff accepts 2 parameters: path, staged. The full parameter table on this page comes from the server's own tool schema.
Register the Breakpoint MCP server in PolicyLayer and add a rule for vcs_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 Breakpoint. Nothing to install.
vcs_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 vcs_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 vcs_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.
vcs_diff is provided by the Breakpoint MCP server (breakpoint-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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