This record as markdown: /tools/io-tinyfn-tinyfn/array-fill.md
What array_fill does on TinyFn
AI agents use array_fill to create or update resources in TinyFn, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your TinyFn environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
value | string | Yes | Value to fill |
length | integer | Yes | Array length |
Parameters from the server's own tool schema.
Why array_fill is rated Medium
This tool creates a new array filled with a specified value. It is a Write operation because it constructs/creates data, though the data structure is typically temporary and in-memory. Severity is low because the operation is reversible (the array can be discarded), affects only local state, and has no external side effects, destructive consequences, or financial impact.
From the tool's definition Tool name 'array_fill' and description 'Create an array filled with a value' indicate the tool creates/instantiates a new data structure in memory.
Attacks that exploit this kind of access
The rule that runs array_fill 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 array_fill, this is the rule to start with:
array_fill stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. 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 array_fill call is checked against it from then on.
Questions about array_fill
Create an array filled with a value. It is categorised as a Write tool in the TinyFn MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
array_fill accepts 2 parameters: value, length. Required: value, length. 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 array_fill: 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.
array_fill 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 array_fill 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 array_fill. 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.
array_fill 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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