check_owner

THE RISK

Low Risk

Why check_owner needs a policy

This is a read-only operation that retrieves ownership information about blockchain assets. It does not modify, execute code, delete data, or move funds. The blast radius of misuse (e.g., checking ownership of many addresses) is minimal and informational only.

From the tool's definition Tool name is 'check_owner' and description states it 'Check if a wallet owns a specific token or NFT' — a pure query operation with no side effects.

Documented attack patterns abuse exactly the kind of access check_owner gives an agent:

POLICY

How to control check_owner

PolicyLayer is an MCP gateway — it sits between your AI agents and Tatum MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for check_owner:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "check_owner": {}
  }
}

check_owner is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Tatum MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Tatum MCP Server tools

Execute gateway_execute_rpc Execute blockchain RPC calls through Tatum Read check_malicious_address Check if a blockchain address is flagged as malicious. Read gateway_get_supported_chains Get a list of all supported blockchain networks available through Tatum Read gateway_get_supported_methods Get supported RPC methods for a specific blockchain chain Read get_block_by_time Get block number closest to a given time or timestamp. Read get_exchange_rate Get current exchange rate for a specific cryptocurrency symbol. Read get_metadata Fetch metadata of NFTs or multitokens by token address and IDs. Read get_owners Get all addresses owning a specific NFT, multitoken, or ERC-20.

All 13 Tatum MCP Server tools →

Read tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about check_owner

What does the check_owner tool do? +

Check if a wallet owns a specific token or NFT. It is categorised as a Read tool in the Tatum MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on check_owner? +

Register the Tatum MCP Server MCP server in PolicyLayer and add a rule for check_owner: 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 Tatum MCP Server. Nothing to install.

What risk level is check_owner? +

check_owner is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit check_owner? +

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

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

check_owner is provided by the Tatum MCP Server MCP server (tatumio/blockchain-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Tatum MCP Server tool call.

Start from Tatum MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →