stream_start · TradingView MCP: Risk & Policy

WHAT IT DOES

What stream_start does on TradingView MCP

AI agents invoke stream_start to trigger actions in TradingView MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why stream_start needs a policy

The tool initiates an ongoing external operation — a live data stream connected to TradingView — that triggers continuous data collection and buffering. This goes beyond a passive read: it starts a persistent process/session with side effects (allocating a stream buffer, maintaining a connection). This qualifies as Execute.

From the tool's definition 'Start a live streaming buffer for quote/bars/values. Returns a stream_id. Claude then calls stream_read to drain accumulated changes.'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

stream_start Rate-limited

stream_start stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "stream_start": {
      "limits": [
        {
          "counter": "stream_start_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about stream_start

What does the stream_start tool do? +

Start a live streaming buffer for quote/bars/values. Returns a stream_id. Claude then calls stream_read to drain accumulated changes. Use this for. It is categorised as a Execute tool in the TradingView MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on stream_start? +

Register the TradingView MCP server in PolicyLayer and add a rule for stream_start: 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 TradingView MCP. Nothing to install.

What risk level is stream_start? +

stream_start is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit stream_start? +

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

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

stream_start is provided by the TradingView MCP server (ulianbass/tradingview-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.