add_decision · Project Brain MCP: Risk & Policy

WHAT IT DOES

What add_decision does on Project Brain

AI agents use add_decision to create or update resources in Project Brain — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Project Brain environment.

WHY IT NEEDS A POLICY

Why add_decision needs a policy

The tool creates or stores new decision records in an engineering memory system. This is a Write operation—it modifies the knowledge base by adding data, and the action is reversible (entries can be deleted or updated via sibling tools). It does not destroy data (not Destructive), execute arbitrary code (not Execute), or move money (not Financial).

From the tool's definition Tool name 'add_decision' and sibling tools on the same server include 'add_finding', 'add_mistake', 'update_entry', 'delete_entry'. This indicates a data management system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_decision Rate-limited

add_decision 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": {
    "add_decision": {
      "limits": [
        {
          "counter": "add_decision_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 Project Brain, so you can run agents against it safely.

FAQ

Questions about add_decision

What does the add_decision tool do? +

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

How do I enforce a policy on add_decision? +

Register the Project Brain MCP server in PolicyLayer and add a rule for add_decision: 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 Project Brain. Nothing to install.

What risk level is add_decision? +

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

Can I rate-limit add_decision? +

Yes. Add a rate_limit block to the add_decision 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 add_decision completely? +

Set action: deny in the PolicyLayer policy for add_decision. 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 add_decision? +

add_decision is provided by the Project Brain MCP server (pym2282/project-brain-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.