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jmespath-mcp

jmespath-mcp

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github.com/MukundaKattaDeveloper Tools0Updated 20w ago
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About jmespath-mcp

jmespath-mcp is an MCP server for querying JSON with JMESPath, aimed at workflows that need projections, filters, and built-in functions. Its implementation is pure JavaScript and requires no native binary.

Key features

  1. 01Run JMESPath expressions on JSON
  2. 02Project and filter arrays
  3. 03Use pipes and built-in functions
  4. 04Pure JavaScript; no native binary

Use cases

  1. 01Select nested JSON values
  2. 02Filter and project array entries
  3. 03Sort values or calculate JSON properties

MCP support

It exposes the `json_query` tool to MCP clients, which runs a JMESPath expression against supplied JSON data.

Configuration

Local server config is the same for every client. Copy it into your client’s MCP config file.

mcp.json · Universal config
{
  "mcpServers": {
    "mukundakatta-jmespath": {
      "command": "npx",
      "args": [
        "-y",
        "@mukundakatta/jmespath-mcp"
      ]
    }
  }
}
Run commandnpx -y @mukundakatta/jmespath-mcp

Local servers need a runtime on your machine (e.g. Node.js 18+). Config file locations differ by client; see your client’s docs.

Packages
npm@mukundakatta/jmespath-mcp0.1.0

Tools

1

Saved tool list · updated 3w ago

ParameterTypeRequiredDescription
dataanyYesJSON to query. Pass as a JSON string OR a pre-parsed value.
expressionstringYesJMESPath expression. Examples: foo.bar | items[*].name | locations[?state=='WA'].name | length(@).

Details

From the project 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

{
  "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.

Comments

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