universal-json-agent-mcp 0.1.2

MCP server for advanced JSON parsing — load, query, aggregate, transform any JSON file from GitHub Copilot, Claude, Cursor, or any MCP client.

Universal JSON Agent MCP

An MCP server for parsing, querying, and analysing JSON files — installable from PyPI.

pip install universal-json-agent-mcp

26 tools for loading, exploring, querying, aggregating, transforming, and exporting JSON — usable from GitHub Copilot, Claude Desktop, Cursor, or any MCP client.

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Table of Contents

• Quick Start
• MCP Client Configuration
• Web API Server (Optional)
• Tools Reference
• Development
• Project Structure
• Testing
• Configuration
• Troubleshooting

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Quick Start

Install

pip install universal-json-agent-mcp
# or
uv add universal-json-agent-mcp

Run

universal-json-agent-mcp
# or
python -m universal_json_agent_mcp

The server starts on stdio — connect any MCP client to it.

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MCP Client Configuration

VS Code / GitHub Copilot

Add to .vscode/mcp.json in your workspace:

{
  "servers": {
    "universal-json-agent": {
      "type": "stdio",
      "command": "universal-json-agent-mcp"
    }
  }
}

Or use uvx (no install needed):

{
  "servers": {
    "universal-json-agent": {
      "type": "stdio",
      "command": "uvx",
      "args": ["universal-json-agent-mcp"]
    }
  }
}

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "universal-json-agent": {
      "command": "universal-json-agent-mcp"
    }
  }
}

Cursor

Add to Cursor's MCP settings:

{
  "mcpServers": {
    "universal-json-agent": {
      "command": "universal-json-agent-mcp"
    }
  }
}

Example prompts

Once connected, ask natural-language questions in your AI chat:

Load the file data/orders.json and tell me what's in it
How many missions are there?
What are the codenames of all missions with status "in_progress"?
What's the total budget across all missions?
Sort missions by budget descending
Get all personnel names using JSONPath

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Web API Server (Optional)

The repo also includes a standalone FastAPI + LangChain web server that wraps the same 26 tools behind a REST API. See web/ for details.

# Install web dependencies
pip install -r web/requirements.txt

# Set your OpenRouter API key
cp .env.example .env   # then edit .env

# Start the server
python -m web.run --port 8000

Endpoints: GET /health, POST /query (file upload), POST /query/path (file on disk). Swagger UI at /docs.

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Tools Reference

Load & Manage

Tool	Description
load_json	Load a JSON file from disk into memory
list_loaded	Show all loaded documents with metadata
unload_json	Remove a document from memory

Explore

Tool	Description
get_keys	Get keys (object) or index range (array) at a path
get_value	Retrieve the value at a path (auto-truncated at 10KB)
get_type	Return the JSON type at a path
get_structure	Schema-like skeleton showing keys and types

Query

Tool	Description
jsonpath_query	Execute a JSONPath expression (e.g. $.users[*].email)
filter_objects	Filter arrays by a field condition (eq, gt, lt, contains, regex…)
search_text	Recursively search all string values for a substring or regex

Aggregate

Tool	Description
count	Count items in an array or keys in an object
sum_values	Sum numeric values at a JSONPath
min_max	Get min and max of numeric values
unique_values	Get distinct values at a JSONPath
value_counts	Frequency table of values (like pandas value_counts())

Transform

Tool	Description
flatten	Flatten nested objects into dot-notation key-value pairs
pick_fields	Project specific fields from array objects
group_by	Group array objects by a field value
sort_by	Sort array objects by a field
sample	Return N random items from an array

Analytics

Tool	Description
describe	Statistical summary (count, mean, std, min, max, percentiles)
multi_filter	Filter with multiple AND/OR conditions
compare	Diff two JSON values — added/removed keys, type/value changes

Export

Tool	Description
export_csv	Export an array of objects to CSV
export_json	Export a value at a path to a new JSON file

Introspect

Tool	Description
distinct_paths	List every unique leaf path in a document with types

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Development

# Clone and install for development
git clone https://github.com/GautamVhavle/universal-json-agent.git
cd universal-json-agent
uv sync --extra dev

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Project Structure

universal-json-agent/
├── src/universal_json_agent_mcp/     # Installable MCP server package
│   ├── __init__.py
│   ├── __main__.py                   # python -m universal_json_agent_mcp
│   ├── server.py                     # MCP entry point — registers all 26 tools
│   ├── store.py                      # In-memory document store with metadata
│   ├── tools/
│   │   ├── load.py                   # load_json, list_loaded, unload_json
│   │   ├── explore.py                # get_keys, get_value, get_type, get_structure
│   │   ├── query.py                  # jsonpath_query, filter_objects, search_text
│   │   ├── aggregate.py              # count, sum_values, min_max, unique_values, value_counts
│   │   ├── transform.py              # flatten, pick_fields, group_by, sort_by, sample
│   │   ├── stats.py                  # describe
│   │   ├── advanced_query.py         # multi_filter, compare
│   │   ├── export.py                 # export_csv, export_json
│   │   └── introspect.py             # distinct_paths
│   └── utils/
│       ├── path_resolver.py          # Dot/bracket path navigation
│       └── truncation.py             # Smart output capping
│
├── web/                              # Optional FastAPI + LangChain web server
├── tests/                            # 489 tests
├── pyproject.toml                    # Package metadata (PyPI)
├── LICENSE                           # MIT
└── sample.json                       # Example JSON file

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Testing

# Run all tests
uv run pytest

# Run with verbose output
uv run pytest -v

# Run a specific test file
uv run pytest tests/test_tools/test_aggregate.py

# Run tests matching a name pattern
uv run pytest -k "test_filter"

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Configuration

Environment variables

Variable	Required	Default	Description
OPENROUTER_API_KEY	Yes (web only)	—	Your OpenRouter API key
OPENROUTER_MODEL	No	openai/gpt-4o-mini	Any model from openrouter.ai/models

MCP server config

The MCP server requires no configuration. It's registered via .vscode/mcp.json and uses stdio transport.

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Troubleshooting

Problem	Solution
MCP server not appearing in Copilot	Make sure .vscode/mcp.json exists and the workspace is open. Restart VS Code.
"No document loaded" errors	Call load_json first before querying.
Truncated output	Large results are capped at ~10KB. Use specific paths or filters to narrow results.
OPENROUTER_API_KEY not set	Create a .env file from .env.example and add your key.
429 Too Many Requests	You're rate-limited by the model provider. Wait a moment or switch to a different model.
Import errors in web server	Run uv pip install -r web/requirements.txt to install web dependencies.