Jmespath Mcp

@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

{  "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.