Sign multiple PSBTs in a single call.
AI agents use btc_sign_batch_psbt 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.
Signing PSBTs is the cryptographic authorization step that enables Bitcoin transactions to be finalized and broadcast to the network. While signing alone doesn't move funds, it commits the wallet's authorization to potentially multiple financial transactions at once.
From the tool's definition Sign multiple PSBTs in a single call — signing PSBTs (Partially Signed Bitcoin Transactions) authorizes Bitcoin transactions for broadcast, directly enabling movement of funds.
Attacks that exploit this kind of access
Sign multiple PSBTs in a single call. 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 btc_sign_batch_psbt: 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.
btc_sign_batch_psbt 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 btc_sign_batch_psbt 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 btc_sign_batch_psbt. 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.
btc_sign_batch_psbt 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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