session_add_variable · Z3/SMT MCP Server MCP: Risk & Policy

WHAT IT DOES

What session_add_variable does on Z3/SMT MCP Server

AI agents use session_add_variable to create or update resources in Z3/SMT MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Z3/SMT MCP Server environment.

WHY IT NEEDS A POLICY

Why session_add_variable needs a policy

This tool creates or modifies session state within the Z3 solver reversibly—variables can be removed via session_pop or session_reset. It does not execute arbitrary code, delete data irreversibly, or move money. The empty description lowers confidence slightly, but the naming pattern and context clearly indicate Write semantics.

From the tool's definition Tool name 'session_add_variable' indicates modification of session state by adding a variable to an active Z3 solver session.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

session_add_variable Rate-limited

session_add_variable stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "session_add_variable": {
      "limits": [
        {
          "counter": "session_add_variable_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Z3/SMT MCP Server, so you can run agents against it safely.

FAQ

Questions about session_add_variable

What does the session_add_variable tool do? +

session_add_variable. It is categorised as a Write tool in the Z3/SMT MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on session_add_variable? +

Register the Z3/SMT MCP Server MCP server in PolicyLayer and add a rule for session_add_variable: 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 Z3/SMT MCP Server. Nothing to install.

What risk level is session_add_variable? +

session_add_variable is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit session_add_variable? +

Yes. Add a rate_limit block to the session_add_variable 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.

How do I block session_add_variable completely? +

Set action: deny in the PolicyLayer policy for session_add_variable. 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.

What MCP server provides session_add_variable? +

session_add_variable is provided by the Z3/SMT MCP Server MCP server (newjerseystyle/z3smt-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.