Jmespath Mcp

io.github.MukundaKattaPublished by GitHub account MukundaKattav0.1.0Updated Oct 24, 2026

Run JMESPath queries against JSON. Pure JS, no native binary needed.

VerifiedSTDIODesktop onlyDeveloper ToolsData & Analytics

Overview

AI-generated overview

A local MCP server that runs JMESPath expressions against JSON, letting an assistant filter, project and reshape JSON data reliably.

What you can do
Run a JMESPath expression against supplied JSON data and return the result, using one tool, json_query(expression, data). Handle nested key access, array projections, filters, pipes and built-in functions such as length, sort_by, contains and keys. Perform round-trips through to_entries and from_entries. Works the same on macOS, Linux and Windows because it is pure JavaScript.
When to use it
Useful when an assistant needs to query or reshape JSON with filters, projections or built-in functions that it tends to get wrong when writing paths by hand, and you want the real JMESPath engine to evaluate the expression instead.
Requirements
Runs as a local process over stdio, installed with npx from the npm package @mukundakatta/jmespath-mcp, so Node.js and network access for the package download are needed. No authentication, environment variables or headers are declared.
Before you install
The JSON data passed to the tool is sent to the locally running server process for evaluation; check that this is acceptable for sensitive data. No credentials, payments or write actions are indicated.

Installation

In SourceWeft

  1. Open Jmespath Mcp in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

@mukundakatta/jmespath-mcp

MCP server for JMESPath JSON queries. One tool: json_query(expression, data). Pure JavaScript implementation, no jq binary needed (works the same on macOS / Linux / Windows).

Why this exists

LLMs handle shallow JSON paths well (foo.bar.baz) but reliably mess up:

  • Array projections (people[*].name)
  • Filters (locations[?state == 'WA'])
  • Pipes and built-in functions (length, sort_by, contains, keys)
  • Round-trips through to_entries / from_entries

JMESPath is the AWS-standardized query language for JSON. This server runs your expression through the real JMESPath engine and returns the result.

Why JMESPath instead of jq?

node-jq requires a postinstall step that downloads the jq binary, which fails reliably on Windows. JMESPath is pure JavaScript with no native dependencies. The query language is similar enough for most LLM use-cases (deep paths, filters, projections, built-ins).

Install — Claude Desktop

json
{  "mcpServers": {    "jmespath": { "command": "npx", "args": ["-y", "@mukundakatta/jmespath-mcp"] }  }}

Same shape for Cursor / Cline / Windsurf / Zed.

Tutorial

See https://jmespath.org/tutorial.html for the language. Common patterns:

  • foo.bar — nested key access
  • people[*].name — pluck from each item
  • people[?age > \30`].name` — filter then project
  • sort_by(people, &age)[*].name — sort + project
  • keys(@), values(@), length(@) — basic functions

License

MIT OR Apache-2.0.

Source: packages/jmespath-mcp/README.md at commit 6fad5bb

Tools

0
SourceWeft has not started this package in its sandbox yet, so its tools are not known.

Version history

1
  1. v0.1.0LatestSep 16, 2026

Score

50% of the applicable checks met

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  • Reached in the last 30 days25 pts

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  • Auth declared10 pts

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  • Tools listed15 pts

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  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts