zb_graphql_query · Zion MCP: Risk & Policy

WHAT IT DOES

What zb_graphql_query does on Zion

AI agents invoke zb_graphql_query to trigger actions in Zion. 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.

PARAMETERS

Parameter	Type	Required	Description
`query`	string	Yes
`variables`	object	—

Parameters from the server's own tool schema.

WHY IT NEEDS A POLICY

Why zb_graphql_query needs a policy

A GraphQL passthrough that accepts arbitrary query strings and variables can execute any GraphQL operation including mutations that create, update, or delete data. The word 'Guarded' suggests some access controls exist, but the tool fundamentally allows execution of arbitrary GraphQL operations whose effects depend entirely on the provided query string.

From the tool's definition "GraphQL passthrough" with "query string and variables" — arbitrary GraphQL operations can include mutations, subscriptions, or complex queries beyond simple reads

Risk signalsAccepts freeform code/query input (query)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

zb_graphql_query Rate-limited

zb_graphql_query 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": {
    "zb_graphql_query": {
      "limits": [
        {
          "counter": "zb_graphql_query_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 Zion, so you can run agents against it safely.

FAQ

Questions about zb_graphql_query

What does the zb_graphql_query tool do? +

Guarded Zion Backend GraphQL passthrough. Provide a query string and variables. It is categorised as a Execute tool in the Zion MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

What parameters does zb_graphql_query accept? +

zb_graphql_query accepts 2 parameters: query, variables. Required: query. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on zb_graphql_query? +

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

What risk level is zb_graphql_query? +

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

Can I rate-limit zb_graphql_query? +

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

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

zb_graphql_query is provided by the Zion MCP server (zion-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.