---
title: "tool si.read.explain_catch"
description: "the match: the conditions that admitted it, the words each matched, the observation, and the source."
section: reference
address: /reference/tools/si-read-explain_catch
contract: 0476e35e6e275db5
---

# tool si.read.explain_catch

the match: the conditions that admitted it, the words each matched, the observation, and the source.

[figure: Over MCP, si.read.explain_catch takes UnitRef and returns a card whose body is Catch.]

the conditions that admitted it, the words each matched, the observation, and the source. The call needs the read grant at the strategy rung.



| | |
|---|---|
| input | [UnitRef](/concepts/unitref) |
| result | a card whose body is [Catch](/concepts/catch) |
| read-only | yes |
| destructive | no |
| card address | `ui://scale-intelligence/cards/Catch` |
| HTTP route | [`/v1/read/explain_catch`](/reference/read/explain_catch) |





| field | type | required | note |
|---|---|---|---|
| `id` | `id` | yes |  |
| `kind` | [Kind](/concepts/kind) | yes |  |