Transfer a SIP-9 non-fungible token. Calls the NFT contract
AI agents use stx_transfer_sip9_nft to commit financial operations through Bitcoin wallet MCP server — usually the final step of a payment, billing, or trading workflow. A call moves real money.
While the tool could be classified as 'Execute' (since it triggers an external blockchain operation), the Financial category is more appropriate because: (1) NFTs represent ownership of digital assets with real economic value, (2) the tool directly moves these assets between accounts, (3) this creates irreversible financial obligations and value transfers on-chain, and (4) Financial > Execute in severity hierarchy.
From the tool's definition Tool enables transfer of non-fungible tokens (SIP-9 NFTs) on the Stacks blockchain, which are digital assets with monetary value.
Attacks that exploit this kind of access
Transfer a SIP-9 non-fungible token. Calls the NFT contract. It is categorised as a Financial tool in the Bitcoin wallet MCP server MCP Server, which means it involves financial transactions. Block by default and require explicit approval.
Register the Bitcoin wallet MCP server MCP server in PolicyLayer and add a rule for stx_transfer_sip9_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 Bitcoin wallet MCP server. Nothing to install.
stx_transfer_sip9_nft is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the stx_transfer_sip9_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 stx_transfer_sip9_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.
stx_transfer_sip9_nft is provided by the Bitcoin wallet MCP server MCP server (markmhendrickson/mcp-server-bitcoin). 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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