get_graph_diff
[MAINTENANCE] Read-only: compare the latest code-graph snapshots of two sessions — returns delta in node_count, hotspot_count, and file_churn. Use snapshot_graph_metrics first to record each session's current state.
This record as markdown: /tools/io-github-ajc3xc-meridian/get-graph-diff.md
What get_graph_diff does on Meridian
AI agents call get_graph_diff to retrieve information from Meridian 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 |
|---|---|---|---|
session_a | string | Yes | First session ID. |
session_b | string | Yes | Second session ID to compare against session_a. |
Parameters from the server's own tool schema.
Why get_graph_diff is rated Low
get_graph_diff retrieves and compares existing code-graph data between sessions, returning only derived metrics (deltas). It performs no writes, deletions, or external operations. The [MAINTENANCE] tag and explicit read-only designation confirm this is a non-mutating query tool. Low severity because misuse would only expose code metrics without capability to modify or execute anything.
From the tool's definition Tool description explicitly states 'Read-only: compare the latest code-graph snapshots' and 'returns delta in node_count, hotspot_count, and file_churn' — a pure retrieval and comparison operation with no side effects.
Attacks that exploit this kind of access
The rule that runs get_graph_diff safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Meridian, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For get_graph_diff, this is the rule to start with:
get_graph_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 Meridian, apply this rule, and every get_graph_diff call is checked against it from then on.
Questions about get_graph_diff
[MAINTENANCE] Read-only: compare the latest code-graph snapshots of two sessions — returns delta in node_count, hotspot_count, and file_churn. Use snapshot_graph_metrics first to record each session's current state. It is categorised as a Read tool in the Meridian MCP Server, which means it retrieves data without modifying state.
get_graph_diff accepts 2 parameters: session_a, session_b. Required: session_a, session_b. The full parameter table on this page comes from the server's own tool schema.
Register the Meridian MCP server in PolicyLayer and add a rule for get_graph_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 Meridian. Nothing to install.
get_graph_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 get_graph_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 get_graph_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.
get_graph_diff is provided by the Meridian MCP server (@meridianmcp/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
More on Meridian, and thousands of servers like it.
This server
Across the catalogue