Attach a local file (max 10MB) to a transaction. Allowed types: image/jpeg, image/png, image/heic, image/heif, application/pdf. The file is read from the local filesystem of the host running this MCP server.
Part of the Lunch Money server.
Free to start. No card required.
AI agents use attach_file_to_transaction to create or modify resources in Lunch Money. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call attach_file_to_transaction repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Lunch Money.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"attach_file_to_transaction": {
"limits": [
{
"counter": "attach_file_to_transaction_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Lunch Money policy for all 44 tools.
These attack patterns abuse exactly the kind of access attach_file_to_transaction gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Attach a local file (max 10MB) to a transaction. Allowed types: image/jpeg, image/png, image/heic, image/heif, application/pdf. The file is read from the local filesystem of the host running this MCP server.. It is categorised as a Write tool in the Lunch Money MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Lunch Money MCP server in PolicyLayer and add a rule for attach_file_to_transaction: 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 Lunch Money. Nothing to install.
attach_file_to_transaction 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 attach_file_to_transaction 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 attach_file_to_transaction. 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.
attach_file_to_transaction is provided by the Lunch Money MCP server (@akutishevsky/lunchmoney-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 44 Lunch Money tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.