This record as markdown: /tools/io-tinyfn-tinyfn/subtract-time.md
What subtract_time does on TinyFn
AI agents call subtract_time to retrieve information from TinyFn without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
date | string | Yes | Start date (ISO format) |
days | integer | — | Days to subtract |
hours | integer | — | Hours to subtract |
weeks | integer | — | Weeks to subtract |
minutes | integer | — | Minutes to subtract |
seconds | integer | — | Seconds to subtract |
Parameters from the server's own tool schema.
Why subtract_time is rated Low
Date/time manipulation for computation is a read-like operation. The tool accepts inputs and returns a computed result. It has no destructive, financial, or execution implications. Severity is low because misuse would at worst produce incorrect date calculations with no external blast radius.
From the tool's definition Tool performs date/time arithmetic ('Subtract time from a date'). This is a deterministic calculation with no side effects—it computes and returns a result without modifying state, creating, deleting, or executing external code.
Attacks that exploit this kind of access
The rule that runs subtract_time safely
PolicyLayer is an MCP gateway: it sits between your AI agents and TinyFn, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For subtract_time, this is the rule to start with:
subtract_time is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect TinyFn, apply this rule, and every subtract_time call is checked against it from then on.
Questions about subtract_time
Subtract time from a date. It is categorised as a Read tool in the TinyFn MCP Server, which means it retrieves data without modifying state.
subtract_time accepts 6 parameters: date, days, hours, weeks, minutes, seconds. Required: date. The full parameter table on this page comes from the server's own tool schema.
Register the TinyFn MCP server in PolicyLayer and add a rule for subtract_time: 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 TinyFn. Nothing to install.
subtract_time is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the subtract_time 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 subtract_time. 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.
subtract_time is provided by the TinyFn MCP server (https://api.tinyfn.io/mcp/all/). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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