Live ERC-721 NFT read (Base, Ethereum, Polygon, Arbitrum, Optimism; keyless). Given a contract + tokenId: returns current owner, collection name/symbol, and tokenURI (IPFS auto-resolved to a gateway URL). Pass metadata=1 to also fetch and normalize the token\
AI agents call crypto.nft to retrieve information from Mcp without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries blockchain state for NFT data without modifying it. It retrieves owner information, collection metadata, and token URIs across multiple EVM chains. There are no side effects, no code execution triggered by arguments, no data modification, and no financial transactions.
From the tool's definition Tool performs 'Live ERC-721 NFT read' and 'returns current owner, collection name/symbol, and tokenURI'. The verb 'read' and 'returns' clearly indicate data retrieval only. The 'fetch and normalize' metadata operation is also retrieval-based.
Attacks that exploit this kind of access
Live ERC-721 NFT read (Base, Ethereum, Polygon, Arbitrum, Optimism; keyless). Given a contract + tokenId: returns current owner, collection name/symbol, and tokenURI (IPFS auto-resolved to a gateway URL). Pass metadata=1 to also fetch and normalize the token\. It is categorised as a Read tool in the Mcp MCP Server, which means it retrieves data without modifying state.
Register the MCP server in PolicyLayer and add a rule for crypto.nft: 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. Nothing to install.
crypto.nft is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the crypto.nft 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.
Set action: deny in the PolicyLayer policy for crypto.nft. 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.
crypto.nft is provided by the MCP server (@2sio/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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