csb_build_card_index · Scryfall MCP Server MCP

WHAT IT DOES

What csb_build_card_index does on Scryfall MCP Server

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

WHY IT NEEDS A POLICY

Why csb_build_card_index needs a policy

This tool rebuilds an index and writes it to cache storage. It modifies persistent data (the cache) but is reversible in the sense that the index can be rebuilt again. It is a Write operation, not Destructive, because rebuilding an index is an update/overwrite of derived data rather than a permanent deletion of source data. Severity is medium since misuse could corrupt the index used by other tools for card lookups.

From the tool's definition 'Rebuild oracleId→CSB id index and write cache' — explicitly writes/updates a cache index

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

csb_build_card_index Rate-limited

csb_build_card_index 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": {
    "csb_build_card_index": {
      "limits": [
        {
          "counter": "csb_build_card_index_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

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

FAQ

Questions about csb_build_card_index

What does the csb_build_card_index tool do? +

Rebuild oracleId→CSB id index and write cache. It is categorised as a Write tool in the Scryfall MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on csb_build_card_index? +

Register the Scryfall MCP Server MCP server in PolicyLayer and add a rule for csb_build_card_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 Scryfall MCP Server. Nothing to install.

What risk level is csb_build_card_index? +

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

Can I rate-limit csb_build_card_index? +

Yes. Add a rate_limit block to the csb_build_card_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 csb_build_card_index completely? +

Set action: deny in the PolicyLayer policy for csb_build_card_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 csb_build_card_index? +

csb_build_card_index is provided by the Scryfall MCP Server MCP server (latte-chan/scryfall-connector). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.