Random Number MCP

random_choices

Choose random items from a list, with optional weights to influence selection probabilities. Ideal for sampling, simulations, or random assignments.

Instructions

Choose k items from population with replacement, optionally weighted.

Args: population: List of items to choose from k: Number of items to choose (default 1) weights: Optional weights for each item (default None for equal weights)

Returns: List of k chosen items

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "population": "<population>"
    },
    "name": "random_choices"
  }
}

Input Schema

Name	Required	Description	Default
`population`	Yes
`k`	No
`weights`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed8 schema fields changedv0.1.0May 2, 2026

removedInput schema / properties / k / title
```
Removed value: -"K"
```

addedInput schema / properties / population / items / anyOf

Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "integer"
+  },
+  {
+    "type": "number"
+  },
+  {
+    "type": "boolean"
+  }
+]

removedInput schema / properties / population / title
```
Removed value: -"Population"
```
removedInput schema / properties / weights / title
```
Removed value: -"Weights"
```

addedOutput schema / description

Added value: +"Generic wrapper for non-object return types."

addedOutput schema / properties / result / items / anyOf

Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "integer"
+  },
+  {
+    "type": "number"
+  },
+  {
+    "type": "boolean"
+  }
+]

removedOutput schema / properties / result / title
```
Removed value: -"Result"
```
removedOutput schema / title
```
Removed value: -"_WrappedResult"
```

First observedv1.0.0Aug 15, 2025

TDQS

A4.2/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries full burden for behavioral transparency. It clearly states the sampling method (with replacement) and optional weighting. However, it does not detail edge cases like empty population or weight mismatches, which are typical for such functions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is highly concise with two purposeful sentences and a parameter list. Every part contributes meaning without redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers the core functionality and return type adequately. Given the presence of an output schema (implied by 'Returns list'), it is mostly complete. Minor omissions like error conditions or weight normalization do not detract significantly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The description adds significant value beyond the input schema by explaining each parameter: population is the list, k is the number of draws, and weights are optional and default to equal weights. This clarifies the purpose of each parameter beyond their types.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool selects k items from a population with replacement, optionally weighted. This distinguishes it from siblings like random_sample (without replacement) and random_float (single value).

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explains what the tool does but does not explicitly state when to use it over alternatives. The context of sibling names implies differentiation, but no direct guidance is provided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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