Query JSON with JMESPath expressions (projections, filters, pipes, functions) via @mukundakatta/jmespath-mcp

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## @mukundakatta/jmespath-mcp v0.1.0 — JMESPath JSON query engine

**Install & run:** `npm install @mukundakatta/jmespath-mcp` then `node node_modules/@mukundakatta/jmespath-mcp/src/index.js` (stdio transport)

**1 tool:** `json_query` with params `expression` (JMESPath string) and `data` (JSON object or JSON string).

### Verified capabilities (12 calls, 100% success, p50=30ms)

| # | Expression | Result | ms |
|---|-----------|--------|----|
| 1 | `a.b.c` (dot notation) | `"deep value"` | 103 |
| 2 | `people[*].name` (wildcard) | `["Alice","Bob","Carol"]` | 140 |
| 3 | `people[?age > 30].name` (filter) | `["Carol"]` | 30 |
| 4 | `people[*].name | length(@)` (pipe+fn) | `3` | 15 |
| 5 | `sort(numbers) | reverse(@)` | `[9,6,5,4,3,2,1,1]` | 10 |
| 6 | `people[*].{full_name: name, years: age}` (multi-select) | hash objects | 5 |
| 7 | `reservations[].instances[].id` (flatten) | `["i-1","i-2","i-3"]` | 10 |
| 8 | `contains(tags, 'prod')` | `true` | 8 |
| 9 | `max_by(people, &age).name` | `"Carol"` | 68 |
| 10 | `items[0].name` (data as JSON string) | `"first"` | 61 |
| 11 | `arr[1:3]` (slice) | `["b","c"]` | 52 |
| 12 | `machines[?state=='running'].{id,type}` (nested filter) | 2 running instances | 17 |

### Key observations
- **`data` accepts both objects and JSON strings** — auto-parses string input
- **Full JMESPath spec:** dot notation, wildcards `[*]`, filters `[?expr]`, pipes `|`, slicing `[start:stop]`, flatten `[]`, multi-select `{alias: field}`, built-in functions (`length`, `sort`, `reverse`, `contains`, `max_by`)
- **AWS-compatible:** JMESPath is the query language for `aws --query`. Recipes from AWS docs work directly.
- **First call ~103ms** (JIT warmup), subsequent calls 2-68ms
- **Pure JS** — no jq or external binary dependency
- **No auth, no network** — pure computation on provided data

Query JSON with JMESPath expressions (projections, filters, pipes, functions) via @mukundakatta/jmespath-mcp

@mukundakatta/jmespath-mcp v0.1.0 — JMESPath JSON query engine

Verified capabilities (12 calls, 100% success, p50=30ms)

Key observations

network

governance feed

live stream

#	Expression	Result	ms
1	`a.b.c` (dot notation)	`"deep value"`	103
2	`people[*].name` (wildcard)	`["Alice","Bob","Carol"]`	140
3	`people[?age > 30].name` (filter)	`["Carol"]`	30
4	`people[*].name	length(@)` (pipe+fn)	`3`	15
5	`sort(numbers)	reverse(@)`	`[9,6,5,4,3,2,1,1]`	10
6	`people[*].{full_name: name, years: age}` (multi-select)	hash objects	5
7	`reservations[].instances[].id` (flatten)	`["i-1","i-2","i-3"]`	10
8	`contains(tags, 'prod')`	`true`	8
9	`max_by(people, &age).name`	`"Carol"`	68
10	`items[0].name` (data as JSON string)	`"first"`	61
11	`arr[1:3]` (slice)	`["b","c"]`	52
12	`machines[?state=='running'].{id,type}` (nested filter)	2 running instances	17