# Topk result check

`topk-result-check` · version 1.0.0 · Numbers & math · free, no key needed

Checks a claimed exact-decimal top-k ranking with deterministic source-index ties.

**Use when you need to: check top k result · validate largest selections · validate smallest selections.**

## Decide before calling

Read the [versioned contract](/v1/tools/topk-result-check/versions/1.0.0) and the supported scope below. Reuse `topk-result-check@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `topk-result-check@1.0.0` for check top k result. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- check top k result
- validate largest selections
- validate smallest selections
- audit top k witnesses
- check ranked claim
- compare claimed top k

## Not supported

- does not approximate numeric values
- does not silently fill missing ranks

## Behavior

- If the complete first-discrepancy verdict would exceed 4,096 UTF-8 JSON bytes, the tool throws limit_exceeded instead of truncating, omitting, or repairing either witness.
- Values are exact decimal strings; ranking is numeric and equal numeric values tie by ascending source index.
- The claim has exactly k witnesses in rank order; source values must not be null.

## Input

- `source` (array of string, required): max items 10000
- `k` (integer, required): min 0; max 10000
- `direction` (one of "largest", "smallest", required)
- `claimed` (array of object, required): max items 10000

## Output

- `valid` (boolean, required)
- `reason` (string, optional)
- `discrepancy` (object, optional)
- `reference_version` (string, required)

## Limits

- max items: 10000
- max input bytes: 1000000
- max output bytes: 4096

## Example

Request input:

```json
{
  "source": [
    "2",
    "10",
    "10.0"
  ],
  "k": 2,
  "direction": "largest",
  "claimed": [
    {
      "source_index": 1,
      "value": "10"
    },
    {
      "source_index": 2,
      "value": "10.0"
    }
  ]
}
```

Response:

```json
{
  "result": {
    "valid": true,
    "reference_version": "ECMA-262-2026-Array-iteration-order+Hoare-1961-selection-invariants"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "topk-result-check",
  "version": "1.0.0",
  "input": {
    "source": [
      "2",
      "10",
      "10.0"
    ],
    "k": 2,
    "direction": "largest",
    "claimed": [
      {
        "source_index": 1,
        "value": "10"
      },
      {
        "source_index": 2,
        "value": "10.0"
      }
    ]
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/topk-result-check/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"source":["2","10","10.0"],"k":2,"direction":"largest","claimed":[{"source_index":1,"value":"10"},{"source_index":2,"value":"10.0"}]}'
```

The machine-readable contract is at [/v1/tools/topk-result-check/versions/1.0.0](/v1/tools/topk-result-check/versions/1.0.0).

### CLI

```sh
node cli.mjs run topk-result-check 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [Dedupe first check](/tools/dedupe-first-check): Check an exact first-wins SameValueZero deduplication claim and report its first discrepancy.
- [Dedupe keyed check](/tools/dedupe-keyed-check): Check an exact keyed Map deduplication claim and report its first discrepancy.
- [Dedupe last check](/tools/dedupe-last-check): Check an exact last-wins SameValueZero deduplication claim and report its first discrepancy.
- [Filter result check](/tools/filter-result-check): Checks an exact claimed decimal filter result with source-order witnesses.
- [Multiset difference check](/tools/multiset-difference-check): Check claimed left-only and right-only scalar bag differences in deterministic source order.
- [Partition result check](/tools/partition-result-check): Checks both sides of a claimed stable decimal partition with source witnesses.