Underground Cultural District MCP Server

format-json

Format JSON strings by pretty-printing for readability, minifying for compactness, or validating for correctness.

Instructions

Pretty-print, minify, or validate a JSON string.

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": {
      "json": "<json>"
    },
    "name": "format-json"
  }
}

Input Schema

Name	Required	Description	Default
`json`	Yes	JSON string
`mode`	No	Operation (default: pretty)	pretty

Schema Changelog

Changes observed during successful MCP inspections.

First observedv4.1.0Apr 17, 2026

TDQS

A3.5/5.0

Behavior2/5

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

No annotations provided. Description does not disclose error handling, response format, or any side effects (e.g., does it throw on invalid JSON?). Minimal behavioral disclosure.

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?

Single sentence that clearly front-loads the three operations. No wasted words, efficient and easy to parse.

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

Completeness3/5

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

No output schema provided; description does not mention return value (e.g., formatted string) or error behavior. For a simple tool, missing output details limit completeness.

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 already fully describes parameters (100% coverage). Description only restates the mode enum values without adding new meaning. Baseline 3 is appropriate.

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?

Description explicitly states the three operations (pretty-print, minify, validate) and the resource (JSON string). Clearly differentiates from sibling tools like encode/decode or hash.

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?

Description lists operations but provides no guidance on when to use each mode, nor mentions alternatives or prerequisites. Lacks when-to-use context.

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