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schema-tools

schema-tools

by rog0x
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Remote

mock_from_schema

Generate realistic mock data from any JSON Schema, with contextual values for emails, names, dates, and more. Supports all schema types and constraints.

Instructions

Generate realistic mock data from a JSON Schema. Uses smart field-name detection to produce contextual values: email fields get valid emails, name fields get realistic names, dates get ISO strings, etc. Supports all JSON Schema types and constraints.

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": {
      "schema": "<schema>"
    },
    "name": "mock_from_schema"
  }
}

Input Schema

NameRequiredDescriptionDefault
seedNoRandom seed for reproducible output. Same seed + same schema = same data.
countNoNumber of mock objects to generate (default: 1). If > 1, returns an array.
schemaYesThe JSON Schema to generate mock data from

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.0.0

TDQS

A3.8/5.0
Behavior3/5

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

No annotations are provided, so the description carries the full burden. It discloses that the tool uses smart field detection and supports all JSON Schema types and constraints, which is useful. However, it does not mention error handling, edge cases, or the exact structure of the returned data beyond what the parameter descriptions imply. This is adequate but not rich.

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 two sentences, front-loading the core purpose and then adding a distinguishing feature. Every word earns its place; no fluff or repetition.

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 tool has no output schema, but the description and parameter docs together cover most needs: it returns mock data, count controls array output, seed ensures reproducibility. Complex behaviors like format constraints are hinted at ('supports all JSON Schema types and constraints'). Missing explicit error behavior, but for a generator tool it is largely complete.

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

Parameters3/5

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

Schema description coverage is 100%, so the schema already documents all parameters. The description adds no extra semantic detail beyond what parameters already state, such as seed behavior or count semantics. Baseline 3 applies since the schema handles the heavy lifting.

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 generates mock data from a JSON Schema, with a specific verb ('Generate') and resource ('mock data from a JSON Schema'). It also highlights the smart field-name detection feature, making its purpose precise and easily distinguishable from sibling tools like generate_typescript or validate_schema.

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 implies when to use this tool (to get sample data from a schema) but does not explicitly contrast it with alternatives. Sibling tools are semantically different, making the choice obvious, yet there is no direct 'when not to use' guidance. It relies on the reader to infer usage context.

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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