Benchmarks test LLM comprehension across different input formats using 209 data retrieval questions on 4 models.

<details>
<summary><strong>Show Dataset Catalog</strong></summary>

#### Dataset Catalog

| Dataset | Rows | Structure | CSV Support | Eligibility |
| ------- | ---- | --------- | ----------- | ----------- |
| Uniform employee records | 100 | uniform | ✓ | 100% |
| E-commerce orders with nested structures | 50 | nested | ✗ | 33% |
| Time-series analytics data | 60 | uniform | ✓ | 100% |
| Top 100 GitHub repositories | 100 | uniform | ✓ | 100% |
| Semi-uniform event logs | 75 | semi-uniform | ✗ | 50% |
| Deeply nested configuration | 11 | deep | ✗ | 0% |
| Valid complete dataset (control) | 20 | uniform | ✓ | 100% |
| Array truncated: 3 rows removed from end | 17 | uniform | ✓ | 100% |
| Extra rows added beyond declared length | 23 | uniform | ✓ | 100% |
| Inconsistent field count (missing salary in row 10) | 20 | uniform | ✓ | 100% |
| Missing required fields (no email in multiple rows) | 20 | uniform | ✓ | 100% |

**Structure classes:**
- **uniform**: All objects have identical fields with primitive values
- **semi-uniform**: Mix of uniform and non-uniform structures
- **nested**: Objects with nested structures (nested objects or arrays)
- **deep**: Highly nested with minimal tabular eligibility

**CSV Support:** ✓ (supported), ✗ (not supported – would require lossy flattening)

**Eligibility:** Percentage of arrays that qualify for TOON's tabular format (uniform objects with primitive values)

</details>

#### Efficiency Ranking (Accuracy per 1K Tokens)

Each format's overall performance, balancing accuracy against token cost:

```
TOON           ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓   26.9  │  73.9% acc  │  2,744 tokens
JSON compact   ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓░░░   22.9  │  70.7% acc  │  3,081 tokens
YAML           ▓▓▓▓▓▓▓▓▓▓▓▓▓▓░░░░░░   18.6  │  69.0% acc  │  3,719 tokens
JSON           ▓▓▓▓▓▓▓▓▓▓▓░░░░░░░░░   15.3  │  69.7% acc  │  4,545 tokens
XML            ▓▓▓▓▓▓▓▓▓▓░░░░░░░░░░   13.0  │  67.1% acc  │  5,167 tokens
```

TOON achieves **73.9%** accuracy (vs JSON's 69.7%) while using **39.6% fewer tokens**.

**Note on CSV:** Excluded from ranking as it only supports 109 of 209 questions (flat tabular data only). While CSV is highly token-efficient for simple tabular data, it cannot represent nested structures that other formats handle.

#### Per-Model Accuracy

Accuracy across 4 LLMs on 209 data retrieval questions:

```
claude-haiku-4-5-20251001
→ TOON           ████████████░░░░░░░░    59.8% (125/209)
  JSON           ███████████░░░░░░░░░    57.4% (120/209)
  YAML           ███████████░░░░░░░░░    56.0% (117/209)
  XML            ███████████░░░░░░░░░    55.5% (116/209)
  JSON compact   ███████████░░░░░░░░░    55.0% (115/209)
  CSV            ██████████░░░░░░░░░░    50.5% (55/109)

gemini-2.5-flash
→ TOON           ██████████████████░░    87.6% (183/209)
  CSV            █████████████████░░░    86.2% (94/109)
  JSON compact   ████████████████░░░░    82.3% (172/209)
  YAML           ████████████████░░░░    79.4% (166/209)
  XML            ████████████████░░░░    79.4% (166/209)
  JSON           ███████████████░░░░░    77.0% (161/209)

gpt-5-nano
→ TOON           ██████████████████░░    90.9% (190/209)
  JSON compact   ██████████████████░░    90.9% (190/209)
  JSON           ██████████████████░░    89.0% (186/209)
  CSV            ██████████████████░░    89.0% (97/109)
  YAML           █████████████████░░░    87.1% (182/209)
  XML            ████████████████░░░░    80.9% (169/209)

grok-4-fast-non-reasoning
→ TOON           ███████████░░░░░░░░░    57.4% (120/209)
  JSON           ███████████░░░░░░░░░    55.5% (116/209)
  JSON compact   ███████████░░░░░░░░░    54.5% (114/209)
  YAML           ███████████░░░░░░░░░    53.6% (112/209)
  XML            ███████████░░░░░░░░░    52.6% (110/209)
  CSV            ██████████░░░░░░░░░░    52.3% (57/109)
```

**Key tradeoff:** TOON achieves **73.9% accuracy** (vs JSON's 69.7%) while using **39.6% fewer tokens** on these datasets.

<details>
<summary><strong>Performance by dataset, model, and question type</strong></summary>

#### Performance by Question Type

| Question Type | TOON | JSON compact | JSON | CSV | YAML | XML |
| ------------- | ---- | ---- | ---- | ---- | ---- | ---- |
| Field Retrieval | 99.6% | 99.3% | 99.3% | 100.0% | 98.2% | 98.9% |
| Aggregation | 54.4% | 47.2% | 48.8% | 44.0% | 47.6% | 41.3% |
| Filtering | 56.3% | 57.3% | 50.5% | 49.1% | 51.0% | 47.9% |
| Structure Awareness | 88.0% | 83.0% | 83.0% | 85.9% | 80.0% | 80.0% |
| Structural Validation | 70.0% | 45.0% | 50.0% | 80.0% | 60.0% | 80.0% |

#### Performance by Dataset

##### Uniform employee records

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `csv` | 72.0% | 2,352 | 118/164 |
| `toon` | 73.8% | 2,518 | 121/164 |
| `json-compact` | 69.5% | 3,953 | 114/164 |
| `yaml` | 68.3% | 4,982 | 112/164 |
| `json-pretty` | 68.3% | 6,360 | 112/164 |
| `xml` | 69.5% | 7,324 | 114/164 |

##### E-commerce orders with nested structures

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `toon` | 81.1% | 7,232 | 133/164 |
| `json-compact` | 76.8% | 6,794 | 126/164 |
| `yaml` | 75.6% | 8,347 | 124/164 |
| `json-pretty` | 76.2% | 10,713 | 125/164 |
| `xml` | 74.4% | 12,023 | 122/164 |

##### Time-series analytics data

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `csv` | 73.3% | 1,406 | 88/120 |
| `toon` | 72.5% | 1,548 | 87/120 |
| `json-compact` | 71.7% | 2,349 | 86/120 |
| `yaml` | 71.7% | 2,949 | 86/120 |
| `json-pretty` | 68.3% | 3,676 | 82/120 |
| `xml` | 68.3% | 4,384 | 82/120 |

##### Top 100 GitHub repositories

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `toon` | 62.9% | 8,780 | 83/132 |
| `csv` | 61.4% | 8,528 | 81/132 |
| `yaml` | 59.8% | 13,142 | 79/132 |
| `json-compact` | 55.3% | 11,465 | 73/132 |
| `json-pretty` | 56.1% | 15,158 | 74/132 |
| `xml` | 48.5% | 17,105 | 64/132 |

##### Semi-uniform event logs

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `json-compact` | 63.3% | 4,819 | 76/120 |
| `toon` | 57.5% | 5,799 | 69/120 |
| `json-pretty` | 59.2% | 6,797 | 71/120 |
| `yaml` | 48.3% | 5,827 | 58/120 |
| `xml` | 46.7% | 7,709 | 56/120 |

##### Deeply nested configuration

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `json-compact` | 92.2% | 574 | 107/116 |
| `toon` | 95.7% | 666 | 111/116 |
| `yaml` | 91.4% | 686 | 106/116 |
| `json-pretty` | 94.0% | 932 | 109/116 |
| `xml` | 92.2% | 1,018 | 107/116 |

##### Valid complete dataset (control)

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `toon` | 100.0% | 544 | 4/4 |
| `json-compact` | 100.0% | 795 | 4/4 |
| `yaml` | 100.0% | 1,003 | 4/4 |
| `json-pretty` | 100.0% | 1,282 | 4/4 |
| `csv` | 25.0% | 492 | 1/4 |
| `xml` | 0.0% | 1,467 | 0/4 |

##### Array truncated: 3 rows removed from end

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `csv` | 100.0% | 425 | 4/4 |
| `xml` | 100.0% | 1,251 | 4/4 |
| `toon` | 0.0% | 474 | 0/4 |
| `json-compact` | 0.0% | 681 | 0/4 |
| `json-pretty` | 0.0% | 1,096 | 0/4 |
| `yaml` | 0.0% | 859 | 0/4 |

##### Extra rows added beyond declared length

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `csv` | 100.0% | 566 | 4/4 |
| `toon` | 75.0% | 621 | 3/4 |
| `xml` | 100.0% | 1,692 | 4/4 |
| `yaml` | 75.0% | 1,157 | 3/4 |
| `json-compact` | 50.0% | 917 | 2/4 |
| `json-pretty` | 50.0% | 1,476 | 2/4 |

##### Inconsistent field count (missing salary in row 10)

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `csv` | 75.0% | 489 | 3/4 |
| `yaml` | 100.0% | 996 | 4/4 |
| `toon` | 100.0% | 1,019 | 4/4 |
| `json-compact` | 75.0% | 790 | 3/4 |
| `xml` | 100.0% | 1,458 | 4/4 |
| `json-pretty` | 75.0% | 1,274 | 3/4 |

##### Missing required fields (no email in multiple rows)

| Format | Accuracy | Tokens | Correct/Total |
| ------ | -------- | ------ | ------------- |
| `csv` | 100.0% | 329 | 4/4 |
| `xml` | 100.0% | 1,411 | 4/4 |
| `toon` | 75.0% | 983 | 3/4 |
| `yaml` | 25.0% | 960 | 1/4 |
| `json-pretty` | 25.0% | 1,230 | 1/4 |
| `json-compact` | 0.0% | 755 | 0/4 |

#### Performance by Model

##### claude-haiku-4-5-20251001

| Format | Accuracy | Correct/Total |
| ------ | -------- | ------------- |
| `toon` | 59.8% | 125/209 |
| `json-pretty` | 57.4% | 120/209 |
| `yaml` | 56.0% | 117/209 |
| `xml` | 55.5% | 116/209 |
| `json-compact` | 55.0% | 115/209 |
| `csv` | 50.5% | 55/109 |

##### gemini-2.5-flash

| Format | Accuracy | Correct/Total |
| ------ | -------- | ------------- |
| `toon` | 87.6% | 183/209 |
| `csv` | 86.2% | 94/109 |
| `json-compact` | 82.3% | 172/209 |
| `yaml` | 79.4% | 166/209 |
| `xml` | 79.4% | 166/209 |
| `json-pretty` | 77.0% | 161/209 |

##### gpt-5-nano

| Format | Accuracy | Correct/Total |
| ------ | -------- | ------------- |
| `toon` | 90.9% | 190/209 |
| `json-compact` | 90.9% | 190/209 |
| `json-pretty` | 89.0% | 186/209 |
| `csv` | 89.0% | 97/109 |
| `yaml` | 87.1% | 182/209 |
| `xml` | 80.9% | 169/209 |

##### grok-4-fast-non-reasoning

| Format | Accuracy | Correct/Total |
| ------ | -------- | ------------- |
| `toon` | 57.4% | 120/209 |
| `json-pretty` | 55.5% | 116/209 |
| `json-compact` | 54.5% | 114/209 |
| `yaml` | 53.6% | 112/209 |
| `xml` | 52.6% | 110/209 |
| `csv` | 52.3% | 57/109 |

</details>

<details>
<summary><strong>How the benchmark works</strong></summary>

#### What's Being Measured

This benchmark tests **LLM comprehension and data retrieval accuracy** across different input formats. Each LLM receives formatted data and must answer questions about it (this does **not** test model's ability to generate TOON output).

#### Datasets Tested

Eleven datasets designed to test different structural patterns and validation capabilities:

**Primary datasets:**
1. **Tabular** (100 employee records): Uniform objects with identical fields – optimal for TOON's tabular format.
2. **Nested** (50 e-commerce orders): Complex structures with nested customer objects and item arrays.
3. **Analytics** (60 days of metrics): Time-series data with dates and numeric values.
4. **GitHub** (100 repositories): Real-world data from top GitHub repos by stars.
5. **Event Logs** (75 logs): Semi-uniform data with ~50% flat logs and ~50% with nested error objects.
6. **Nested Config** (1 configuration): Deeply nested configuration with minimal tabular eligibility.

**Structural validation datasets:**
7. **Control**: Valid complete dataset (baseline for validation)
8. **Truncated**: Array with 3 rows removed from end (tests [N] length detection)
9. **Extra rows**: Array with 3 additional rows beyond declared length
10. **Width mismatch**: Inconsistent field count (missing salary in row 10)
11. **Missing fields**: Systematic field omissions (no email in multiple rows)

#### Question Types

209 questions are generated dynamically across five categories:

- **Field retrieval (33%)**: Direct value lookups or values that can be read straight off a record (including booleans and simple counts such as array lengths)
  - Example: "What is Alice's salary?" → `75000`
  - Example: "How many items are in order ORD-0042?" → `3`
  - Example: "What is the customer name for order ORD-0042?" → `John Doe`

- **Aggregation (30%)**: Dataset-level totals and averages plus single-condition filters (counts, sums, min/max comparisons)
  - Example: "How many employees work in Engineering?" → `17`
  - Example: "What is the total revenue across all orders?" → `45123.50`
  - Example: "How many employees have salary > 80000?" → `23`

- **Filtering (23%)**: Multi-condition queries requiring compound logic (AND constraints across fields)
  - Example: "How many employees in Sales have salary > 80000?" → `5`
  - Example: "How many active employees have more than 10 years of experience?" → `8`

- **Structure awareness (12%)**: Tests format-native structural affordances (TOON's [N] count and {fields}, CSV's header row)
  - Example: "How many employees are in the dataset?" → `100`
  - Example: "List the field names for employees" → `id, name, email, department, salary, yearsExperience, active`
  - Example: "What is the department of the last employee?" → `Sales`

- **Structural validation (2%)**: Tests ability to detect incomplete, truncated, or corrupted data using structural metadata
  - Example: "Is this data complete and valid?" → `YES` (control dataset) or `NO` (corrupted datasets)
  - Tests TOON's [N] length validation and {fields} consistency checking
  - Demonstrates CSV's lack of structural validation capabilities

#### Evaluation Process

1. **Format conversion**: Each dataset is converted to all 6 formats (TOON, JSON compact, JSON, CSV, YAML, XML).
2. **Query LLM**: Each model receives formatted data + question in a prompt and extracts the answer.
3. **Validate deterministically**: Answers are validated using type-aware comparison (e.g., `50000` = `$50,000`, `Engineering` = `engineering`, `2025-01-01` = `January 1, 2025`) without requiring an LLM judge.

#### Models & Configuration

- **Models tested**: `claude-haiku-4-5-20251001`, `gemini-2.5-flash`, `gpt-5-nano`, `grok-4-fast-non-reasoning`
- **Token counting**: Using `gpt-tokenizer` with `o200k_base` encoding (GPT-5 tokenizer)
- **Temperature**: Not set (models use their defaults)
- **Total evaluations**: 209 questions × 6 formats × 4 models = 5,016 LLM calls

</details>