nonce_fill_gap
Fill a nonce gap by sending a minimal STX transfer at the specified nonce. LAST-RESORT recovery action. Each gap-fill is a real on-chain transaction with a real fee (~0.001-0.01 STX). Most gaps self-resolve within seconds as Stacks blocks are 3-5s. Only use this after confirming the gap persists ...
This record as markdown: /tools/io-github-aibtcdev-mcp-server/nonce-fill-gap.md
What nonce_fill_gap does on Aibtc
AI agents use nonce_fill_gap to commit financial operations through Aibtc, usually the final step of a payment, billing, or trading workflow. A call moves real money.
Why nonce_fill_gap is rated Critical
This tool submits real on-chain blockchain transactions that spend STX tokens (both the transfer amount and transaction fees). It commits financial value irreversibly on-chain, qualifying it as Financial. The funds sent to the PoX burn address are unrecoverable, adding a destructive element, but the primary action is a financial transaction on a blockchain network.
From the tool's definition Fill a nonce gap by sending a minimal STX transfer at the specified nonce... Each gap-fill is a real on-chain transaction with a real fee (~0.001-0.01 STX)... fills the gap with a 1 micro-STX transfer to the PoX burn address.
Attacks that exploit this kind of access
The rule that runs nonce_fill_gap safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Aibtc, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For nonce_fill_gap, this is the rule to start with:
Any call to nonce_fill_gap is blocked until a human approves it. The rest of the server keeps working.
The button opens the PolicyLayer dashboard: create your workspace, connect Aibtc, apply this rule, and every nonce_fill_gap call is checked against it from then on.
Questions about nonce_fill_gap
Fill a nonce gap by sending a minimal STX transfer at the specified nonce. LAST-RESORT recovery action. Each gap-fill is a real on-chain transaction with a real fee (~0.001-0.01 STX). Most gaps self-resolve within seconds as Stacks blocks are 3-5s. Only use this after confirming the gap persists via nonce_health. When transactions are pending but a gap exists in the nonce sequence (e.g., nonces 5 and 7 are pending but 6 is missing), the Stacks mempool will not process nonces 7+ until 6 is filled. This tool fills the gap with a 1 micro-STX transfer to the PoX burn address. Use nonce_health first to identify gaps, then call this tool for each missing nonce. Requires the wallet to be unlocked. The fee is auto-estimated. It is categorised as a Financial tool in the Aibtc MCP Server, which means it involves financial transactions. Block by default and require explicit approval.
Register the Aibtc MCP server in PolicyLayer and add a rule for nonce_fill_gap: 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 Aibtc. Nothing to install.
nonce_fill_gap 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 nonce_fill_gap 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 nonce_fill_gap. 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.
nonce_fill_gap is provided by the Aibtc MCP server (aibtcdev/aibtc-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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