agentmods.dev

dataflow-json-schema

A rule for JSON Schema, a format used to describe and restrict structured data, when it controls language-model output in DataFlow. Every object in the schema must explicitly reject fields that are not listed.

In plain words
What is it for?
Use it when writing output schemas in Python generators or the WebUI's operators.json file, including schemas with nested objects.
Why use it?
Without this setting, the service can return an HTTP 500 error and retry forever. Applying the rule to nested objects avoids the same failure deeper in the schema.

Cursor rule for Cursor

220 6d ago A scan 0 tokens original Apache-2.0
View the source file OpenDCAI/DataFlow-WebUI
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/opendcai/dataflow-webui/dataflow-json-schema
Clone the repo
git clone --depth 1 https://github.com/OpenDCAI/DataFlow-WebUI

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 414 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00414
Opus 5 $0.00000 $0.00207
Sonnet 5 $0.00000 $0.00083
Haiku 4.5 $0.00000 $0.00041

Measured 2d ago against content hash 1c75a5398071, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dataflow-json-schema scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/dataflow-json-schema.mdc · 72 lines

What it actually says

DataFlow json_schema: additionalProperties is MANDATORY

When using json_schema in FormatStrPromptedGenerator, PromptedGenerator, or operators.json to constrain LLM structured output:

Every "type": "object" in the schema MUST include "additionalProperties": false.

Without it, OpenAI-compatible APIs return HTTP 500 and DataFlow retries infinitely.

Python (pipeline.py)

# ✅ CORRECT
json_schema={
    "type": "object",
    "properties": {
        "score": {"type": "number"},
        "label": {"type": "string"},
    },
    "required": ["score", "label"],
    "additionalProperties": False,
}

# ❌ WRONG — causes API 500 infinite retry
json_schema={
    "type": "object",
    "properties": {
        "score": {"type": "number"},
        "label": {"type": "string"},
    },
    "required": ["score", "label"],
}

WebUI (operators.json)

{"name": "json_schema", "value": {
    "type": "object",
    "properties": {
        "score": {"type": "number"},
        "label": {"type": "string"}
    },
    "required": ["score", "label"],
    "additionalProperties": false
}}

Nested objects — apply at EVERY level

json_schema={
    "type": "object",
    "properties": {
        "result": {
            "type": "object",
            "properties": {"value": {"type": "number"}},
            "required": ["value"],
            "additionalProperties": False,
        },
    },
    "required": ["result"],
    "additionalProperties": False,
}
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 72 lines · 0 tokens per session scan A 1c75a5398071

Subscribe to this mod's changes

dataflow-json-schema is a cursor rule published in the GitHub repository OpenDCAI/DataFlow-WebUI (220 stars, last pushed 6d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 414 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Data and AILanguagesWriting and docs
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