---
id: DATA-12
family: RT-DATA
level: extended
profiles: [runtime]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/rt-data/data-12
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# DATA-12 — Tools reach only a node that declares itself a tool consumer

*RT-DATA (Part II) · level: extended · profiles: runtime · added in 1.0*

## The rule

> **Normative.** This is the rule.
>
> 1. Tools are handed to a node only where the node type declares that it consumes them.
>
> 2. Wiring tools to a node type that neither consumes nor forwards them is a validation error; a node type that forwards them is accepted and passes them on.
>
> 3. Should such a workflow run regardless, the node receives no tools.
>
> 4. A node re-entered on a later round of a loop receives its tools on every round.


## What it means

A node type that only forwards tools is accepted for wiring even though it
never consumes any of them itself — it exists purely to fan the same tools
out to more than one consumer, and every consumer wired to it sees the whole
set, not a private share carved out for it alone.

The other clause cuts against treating tool binding as something decided once
and then left alone. A node reached again on a later round of a loop is not
running on a binding made the first time it was reached: every round
re-derives which tools it receives, so a node reached a second, third, or
hundredth time still gets everything it is wired to.

## Example

Two calculators, wired as `adder` and `multiplier`, both feed a single shared
forwarding node; that node feeds two separate tool-consuming nodes.

```json title="Each consumer's tool manifest" verdict="listed"
["adder", "multiplier"]
```

A single tool-consuming node sits inside a loop, re-entered on every round,
with one calculator wired to it directly.

```json title="The consumer's tool manifest, every round of the loop" verdict="listed"
["adder"]
```

## Related rules

- Names: DATA-10
- Referenced by: DATA-10

---

Rule identifiers are permanent and are never renumbered. This specification carries
no implementation status: each implementation publishes its own standing against
these rules. Licensed CC BY 4.0.