swarm_build_index · Mcp Swarm MCP: Risk & Policy

WHAT IT DOES

What swarm_build_index does on Mcp Swarm

AI agents invoke swarm_build_index to trigger actions in Mcp Swarm. 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 swarm_build_index needs a policy

Building an index requires scanning the entire codebase and writing index data to storage. This is more than a read operation — it triggers an external operation (index construction) that modifies system state by creating/updating index files. It falls under Execute as it triggers a potentially long-running operation whose effects depend on the codebase contents, though it is not strictly destructive or financial.

From the tool's definition 构建整个代码库的索引，用于快速搜索和导航 (Build an index of the entire codebase for fast search and navigation)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

swarm_build_index Rate-limited

swarm_build_index 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": {
    "swarm_build_index": {
      "limits": [
        {
          "counter": "swarm_build_index_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 Mcp Swarm, so you can run agents against it safely.

FAQ

Questions about swarm_build_index

What does the swarm_build_index tool do? +

构建整个代码库的索引，用于快速搜索和导航。. It is categorised as a Execute tool in the Mcp Swarm MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on swarm_build_index? +

Register the Mcp Swarm MCP server in PolicyLayer and add a rule for swarm_build_index: 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 Mcp Swarm. Nothing to install.

What risk level is swarm_build_index? +

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

Can I rate-limit swarm_build_index? +

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

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

swarm_build_index is provided by the Mcp Swarm MCP server (moselu/mcp-swarm). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.