combine_btc_psbts
Merge 2-15 partial PSBTs from multi-sig cosigners into one whose inputs carry every cosigner's signature. Each entry must be a base64-encoded PSBT v0 sharing the same unsigned tx body (same inputs/outputs/sequences/locktime); only per-cosigner witness data may differ. Refuses with a clear error w...
This record as markdown: /tools/io-github-szhygulin-vaultpilot-mcp/combine-btc-psbts.md
What combine_btc_psbts does on VaultPilot MCP
AI agents invoke combine_btc_psbts to trigger actions in VaultPilot MCP. 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.
| Parameter | Type | Required | Description |
|---|---|---|---|
psbts | array | Yes | Array of 2-15 base64-encoded PSBT v0 strings to merge. Every entry must share the same unsigned tx body (same inputs in the same order, same outputs in the same |
Parameters from the server's own tool schema.
Why combine_btc_psbts is rated High
This tool combines partial Bitcoin PSBTs (Partially Signed Bitcoin Transactions) from multiple cosigners into a single merged PSBT. While it doesn't directly broadcast or finalize a transaction, it aggregates signatures and produces a PSBT that may be threshold-complete and ready for broadcast. This is a critical step in a multi-sig signing flow that enables financial transactions.
From the tool's definition Merge 2-15 partial PSBTs from multi-sig cosigners into one whose inputs carry every cosigner's signature... Returns the merged PSBT plus a per-input signature count so the caller can tell whether the threshold has been reached.
Risk signalsBulk/mass operation — affects multiple targets
Attacks that exploit this kind of access
The rule that runs combine_btc_psbts safely
PolicyLayer is an MCP gateway: it sits between your AI agents and VaultPilot MCP, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For combine_btc_psbts, this is the rule to start with:
combine_btc_psbts 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.
The button opens the PolicyLayer dashboard: create your workspace, connect VaultPilot MCP, apply this rule, and every combine_btc_psbts call is checked against it from then on.
Questions about combine_btc_psbts
Merge 2-15 partial PSBTs from multi-sig cosigners into one whose inputs carry every cosigner's signature. Each entry must be a base64-encoded PSBT v0 sharing the same unsigned tx body (same inputs/outputs/sequences/locktime); only per-cosigner witness data may differ. Refuses with a clear error when bodies disagree — combining across distinct unsigned txs would silently merge signatures across different transactions. Returns the merged PSBT plus a per-input signature count so the caller can tell whether the threshold has been reached. No device touch. It is categorised as a Execute tool in the VaultPilot MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
combine_btc_psbts accepts 1 parameter: psbts. Required: psbts. The full parameter table on this page comes from the server's own tool schema.
Register the VaultPilot MCP server in PolicyLayer and add a rule for combine_btc_psbts: 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 VaultPilot MCP. Nothing to install.
combine_btc_psbts is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the combine_btc_psbts 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 combine_btc_psbts. 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.
combine_btc_psbts is provided by the VaultPilot MCP server (vaultpilot-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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