Add an additional approveHash signature to a Safe (Gnosis Safe) transaction that's ALREADY in the queue (proposed elsewhere — Safe Web UI, another VaultPilot install, or a co-signer). Returns an UnsignedTx that calls Safe.approveHash(safeTxHash) for the given signer; broadcast via send_transactio...
AI agents use prepare_safe_tx_approve to create or update resources in VaultPilot MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your VaultPilot MCP environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
chain | string | — | |
signer | string | Yes | |
safeTxHash | string | Yes | |
safeAddress | string | Yes |
Parameters from the server's own tool schema.
An AI agent can call prepare_safe_tx_approve faster than any human can review — one bad instruction and it creates or modifies resources in VaultPilot MCP by the hundred, each call as confident as the last.
Attacks that exploit this kind of access
Add an additional approveHash signature to a Safe (Gnosis Safe) transaction that's ALREADY in the queue (proposed elsewhere — Safe Web UI, another VaultPilot install, or a co-signer). Returns an UnsignedTx that calls Safe.approveHash(safeTxHash) for the given signer; broadcast via send_transaction, then call submit_safe_tx_signature to push the new signature to Safe Transaction Service. Use prepare_safe_tx_propose instead when you're proposing a NEW Safe tx. It is categorised as a Write tool in the VaultPilot MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
prepare_safe_tx_approve accepts 4 parameters: chain, signer, safeTxHash, safeAddress. Required: signer, safeTxHash, safeAddress. 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 prepare_safe_tx_approve: 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.
prepare_safe_tx_approve is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the prepare_safe_tx_approve 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 prepare_safe_tx_approve. 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.
prepare_safe_tx_approve 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.