log_cost · Agent Cost MCP: Risk & Policy

WHAT IT DOES

What log_cost does on Agent Cost

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

WHY IT NEEDS A POLICY

Why log_cost needs a policy

This tool writes cost and token usage records to the tracking system after each AI interaction. It creates new log entries (a reversible write operation) rather than deleting data, executing code, or moving money. Misuse could corrupt cost tracking data or inflate/deflate reported spending metrics, hence medium severity.

From the tool's definition 'Log token usage and cost for a task. Call this after each AI interaction.' - creates/records cost data entries

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

log_cost Rate-limited

log_cost 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": {
    "log_cost": {
      "limits": [
        {
          "counter": "log_cost_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 Agent Cost, so you can run agents against it safely.

FAQ

Questions about log_cost

What does the log_cost tool do? +

Log token usage and cost for a task. Call this after each AI interaction. It is categorised as a Write tool in the Agent Cost MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on log_cost? +

Register the Agent Cost MCP server in PolicyLayer and add a rule for log_cost: 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 Agent Cost. Nothing to install.

What risk level is log_cost? +

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

Can I rate-limit log_cost? +

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

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

log_cost is provided by the Agent Cost MCP server (vanthienha199/agent-cost-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.