---
url: 'https://adk.nht.io/api/@nhtio/adk/common/interfaces/ToolMethodDescriptor.md'
description: >-
  Metadata table entry for one of the artifact's existing query methods, used by
  [`SpooledArtifact.forgeTools`](https://adk.nht.io/api/@nhtio/adk/spooled_artifact/classes/SpooledArtifact#forgetools) to surface that method as an {@link
  @nhtio/adk!ArtifactTool}.
---

# Interface: ToolMethodDescriptor

Defined in: [lib/classes/spooled\_artifact.ts:48](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/classes/spooled_artifact.ts#L48)

Metadata table entry for one of the artifact's existing query methods, used by
[SpooledArtifact.forgeTools](../../spooled_artifact/classes/SpooledArtifact.md#forgetools) to surface that method as an [@nhtio/adk!ArtifactTool](../../forge/classes/ArtifactTool.md).

## Remarks

This is a metadata shape, not a general method → tool pipeline. `forgeTools` knows how to
marshal arguments for a fixed, closed set of method names (the base seven on
[SpooledArtifact](../../spooled_artifact/classes/SpooledArtifact.md) and the JSON/Markdown methods on the bundled subclasses); a
descriptor is the place to attach a tool name, description, args schema, and optional
serializer to one of those methods. Adding a descriptor for a method whose name is not
in that closed set will produce a tool whose handler invokes the method with no arguments.

For new methods that require custom argument marshalling, branching, multi-step logic,
cross-artifact joins, or any other behaviour beyond "call this existing method," override
[SpooledArtifact.forgeTools](../../spooled_artifact/classes/SpooledArtifact.md#forgetools) and mint the [@nhtio/adk!ArtifactTool](../../forge/classes/ArtifactTool.md) directly — do not try
to express it through a descriptor.

Zero-arg methods are the exception: a descriptor with no `argsSchema` (or one that adds
only `callId`-adjacent fields you don't consume) works for any method that takes no
arguments, regardless of name.

## Properties

| Property                                        | Type                              | Description                                                                                                                                                           | Defined in                                                                                                                    |
| ----------------------------------------------- | --------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- |
|  `argsSchema?`  | `ObjectSchema`<`any`>           | Schema for the method's own args, NOT including `callId`. `forgeTools()` injects `callId`.                                                                            | [lib/classes/spooled\_artifact.ts:56](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/classes/spooled_artifact.ts#L56) |
|  `description` | `string`                          | Human-readable description passed to the model. Should mention "in this turn" so the model understands the artifact's lifecycle scope.                                | [lib/classes/spooled\_artifact.ts:54](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/classes/spooled_artifact.ts#L54) |
|  `method`           | `string`                          | Method to invoke on the resolved artifact instance (e.g. `'head'`, `'json_get'`).                                                                                     | [lib/classes/spooled\_artifact.ts:52](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/classes/spooled_artifact.ts#L52) |
|  `name`               | `string`                          | Absolute tool name as exposed to the LLM (e.g. `'artifact_head'`).                                                                                                    | [lib/classes/spooled\_artifact.ts:50](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/classes/spooled_artifact.ts#L50) |
|  `serialise?`    | (`result`: `unknown`) => `string` | Optional formatter for non-string return values. Defaults: string → as-is; string\[] → newline-join; number → `String(n)`; otherwise `JSON.stringify(value, null, 2)`. | [lib/classes/spooled\_artifact.ts:58](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/classes/spooled_artifact.ts#L58) |