random_weighted_choice
Pick random item(s) with weighted probabilities.
This record as markdown: /tools/io-tinyfn-tinyfn/random-weighted-choice.md
What random_weighted_choice does on TinyFn
AI agents invoke random_weighted_choice to trigger actions in TinyFn. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
| Parameter | Type | Required | Description |
|---|---|---|---|
count | integer | — | Number of choices to make |
items | string | Yes | Comma-separated items (e.g., 'red,green,blue') |
weights | string | Yes | Comma-separated weights (e.g., '50,30,20') |
Parameters from the server's own tool schema.
Why random_weighted_choice is rated High
Although the server claims 500+ 'deterministic' tools, this tool explicitly performs a random weighted choice, making it non-deterministic. It executes a probabilistic selection algorithm. It doesn't read stored data, write/modify persistent data, or destroy anything, so Execute is the closest category.
From the tool's definition 'Pick random item(s) with weighted probabilities' — involves a non-deterministic random selection operation that produces side-effectful output dependent on runtime state
Attacks that exploit this kind of access
The rule that runs random_weighted_choice 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 random_weighted_choice, this is the rule to start with:
random_weighted_choice stays usable, but rate-capped: a runaway agent can't fire it dozens of times 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 random_weighted_choice call is checked against it from then on.
Questions about random_weighted_choice
Pick random item(s) with weighted probabilities. It is categorised as a Execute tool in the TinyFn MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
random_weighted_choice accepts 3 parameters: count, items, weights. Required: items, weights. 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 random_weighted_choice: 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.
random_weighted_choice is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the random_weighted_choice 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 random_weighted_choice. 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.
random_weighted_choice 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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