This record as markdown: /tools/io-tinyfn-tinyfn/subtract.md
What subtract does on TinyFn
AI agents call subtract 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 |
|---|---|---|---|
a | number | Yes | First number |
b | number | Yes | Number to subtract |
Parameters from the server's own tool schema.
Why subtract is rated Low
This is a stateless arithmetic operation that only retrieves/computes a result. It has no capability to modify, delete, execute code, or affect external systems. The blast radius of misuse is negligible—an agent cannot cause harm through mathematical subtraction alone.
From the tool's definition The tool performs a pure mathematical operation 'Subtract b from a' with no side effects, no data modification, and no external state changes. It matches the deterministic math category described in the server description.
Attacks that exploit this kind of access
The rule that runs subtract 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, this is the rule to start with:
subtract 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 call is checked against it from then on.
Questions about subtract
Subtract b from a. It is categorised as a Read tool in the TinyFn MCP Server, which means it retrieves data without modifying state.
subtract accepts 2 parameters: a, b. Required: a, b. 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: 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 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 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. 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 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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