This record as markdown: /tools/io-tinyfn-tinyfn/is-negative.md
What is_negative does on TinyFn
AI agents call is_negative 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 |
|---|---|---|---|
number | number | Yes | The number to check |
Parameters from the server's own tool schema.
Why is_negative is rated Low
This is a simple validation/query function that examines a numeric property and returns a boolean result. It performs no writes, deletes, executions, or financial operations. The blast radius of misuse is negligible—an AI agent cannot cause harm by checking if numbers are negative.
From the tool's definition Tool is named 'is_negative' and described as checking if a number is negative—a pure query operation with no side effects, no state modification, and no execution of external code.
Attacks that exploit this kind of access
The rule that runs is_negative 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 is_negative, this is the rule to start with:
is_negative 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 is_negative call is checked against it from then on.
Questions about is_negative
Check if a number is negative. It is categorised as a Read tool in the TinyFn MCP Server, which means it retrieves data without modifying state.
is_negative accepts 1 parameter: number. Required: number. 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 is_negative: 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.
is_negative 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 is_negative 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 is_negative. 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.
is_negative 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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