> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vendo.run/llms.txt
> Use this file to discover all available pages before exploring further.

# E-TOOLS-004

> Part of the tool catalog declares no request or response shape.

# E-TOOLS-004

<Warning>
  **what doctor prints** (warning)

  catalog: inputs 9/12 · outputs 7/12 — blind: host\_invoices\_list,
  host\_payments\_create; declare them in your OpenAPI/tRPC contract, or run
  `vendo sync` with a model key so the judge reads the handlers
</Warning>

Some tools have no declared request schema, no declared response schema, or
neither. The agent can still call them, just without a contract to bind to.

`check tools/schemas` · `error_code E-TOOLS-004` · `doctor exits 0` (warning only)

## What you're seeing

Doctor counts, per tool, whether its input schema and output schema each
came from a real source (an OpenAPI response schema, a tRPC `.output()`, a
typed server action, or the AI judge) versus `unknown`. It warns whenever at
least one tool is blind on either side, and names up to eight of them.

## Why

Nothing is broken here; a blind tool still runs, permissively. The cost is
precision: the agent cannot know a blind tool's arguments and must not assume
it takes none, and it has to pass a blind tool's whole output through
instead of binding to the two fields a generated screen actually needs.

## The fix

Declare the shape in the contract you already publish. That is the rung that
survives a refactor, since it is generated from your own source of truth
rather than inferred:

```ts theme={null}
export const listInvoices = t.procedure
  .input(z.object({ status: z.enum(["open", "paid"]) }))
  .output(z.array(InvoiceSchema)) // [!code focus]
  .query(...);
```

For handlers with no contract to declare, a bare Next.js route handler for
example, run `vendo sync` with a model key so the judgment pass reads the
handler source and fills the blind slots. It never overwrites a slot your
contract already filled.

Leaving tools blind is safe. It only costs the agent precision.

## Related errors

<CardGroup cols={2}>
  <Card title="E-TOOLS-001" href="/production/troubleshooting/e-tools-001">every tool disabled</Card>
  <Card title="E-TOOLS-002" href="/production/troubleshooting/e-tools-002">tool surface is empty</Card>
  <Card title="E-TOOLS-003" href="/production/troubleshooting/e-tools-003">tools ungraded</Card>
</CardGroup>