Query nested JSON with JSONPath expressions (filter, wildcard, recursive descent, path output) via @mukundakatta/jsonpath-mcp (npx)

@mukundakatta/jsonpath-mcp — JSONPath query engine over MCP

Install & launch:

npm install @mukundakatta/jsonpath-mcp
node node_modules/@mukundakatta/jsonpath-mcp/dist/server.js

Transport: stdio (NDJSON — newline-delimited JSON, NOT Content-Length framing).

Server info: jsonpath v0.1.0, protocol 2024-11-05.

1 tool: query

• json (required) — any JSON value, passed as a raw object (NOT stringified)
• path (required, string) — JSONPath expression, e.g. $.items[*].price
• result_type (optional) — "value" (default), "path", or "all"

Gotcha: json must be a raw JSON object

Passing JSON.stringify(data) as the json param returns empty matches. Pass the object directly — the MCP JSON-RPC layer serializes it.

Verified calls (4 runs, all succeeded):

Filter — books under $10:

{"name":"query","arguments":{"json":{"store":{"book":[{"category":"reference","author":"Nigel Rees","title":"Sayings of the Century","price":8.95},{"category":"fiction","author":"Evelyn Waugh","title":"Sword of Honour","price":12.99},{"category":"fiction","author":"Herman Melville","title":"Moby Dick","isbn":"0-553-21311-3","price":8.99},{"category":"fiction","author":"J. R. R. Tolkien","title":"The Lord of the Rings","isbn":"0-395-19395-8","price":22.99}],"bicycle":{"color":"red","price":19.95}}},"path":"$.store.book[?(@.price<10)]"}}
→ {"matches":[{"category":"reference","author":"Nigel Rees","title":"Sayings of the Century","price":8.95},{"category":"fiction","author":"Herman Melville","title":"Moby Dick","isbn":"0-553-21311-3","price":8.99}]}

Wildcard — all authors:

{"name":"query","arguments":{"json":<same store>,"path":"$.store.book[*].author"}}
→ {"matches":["Nigel Rees","Evelyn Waugh","Herman Melville","J. R. R. Tolkien"]}

Recursive descent — all prices:

{"name":"query","arguments":{"json":<same store>,"path":"$..price"}}
→ {"matches":[8.95,12.99,8.99,22.99,19.95]}

Path output — books with ISBN (result_type=path):

{"name":"query","arguments":{"json":<same store>,"path":"$.store.book[?(@.isbn)]","result_type":"path"}}
→ {"matches":["$['store']['book'][2]","$['store']['book'][3]"]}

Backed by jsonpath-plus. Sub-50ms per call. Credential-free, zero config.