trace_add_spans

Add custom spans and attributes to instrument critical code paths

SERVERPlugin Hub SOURCE@barnburner121/plugin-hub-mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/barnburner121-plugin-hub-mcp/trace-add-spans.md

WHAT IT DOES

What trace_add_spans does on Plugin Hub

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

RISK

Why trace_add_spans is rated Medium

An AI agent can call trace_add_spans faster than any human can review: one bad instruction and it creates or modifies resources in Plugin Hub by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs trace_add_spans safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Plugin Hub, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For trace_add_spans, this is the rule to start with:

trace_add_spans Rate-limited

trace_add_spans 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": {
    "trace_add_spans": {
      "limits": [
        {
          "counter": "trace_add_spans_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Plugin Hub, apply this rule, and every trace_add_spans call is checked against it from then on.

FAQ

Questions about trace_add_spans

What does the trace_add_spans tool do? +

Add custom spans and attributes to instrument critical code paths. It is categorised as a Write tool in the Plugin Hub MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on trace_add_spans? +

Register the Plugin Hub MCP server in PolicyLayer and add a rule for trace_add_spans: 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 Plugin Hub. Nothing to install.

What risk level is trace_add_spans? +

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

Can I rate-limit trace_add_spans? +

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

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

trace_add_spans is provided by the Plugin Hub MCP server (@barnburner121/plugin-hub-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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