Agent SDK reference - TypeScript changedagent-sdk/typescript
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Upstream edited this page at 8 Oct 2026 20:28 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 8 Oct 2026 20:37 UTC.
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238238| `options.version` | `string` | Optional version string |
239239| `options.instructions` | `string` | Optional server instructions, returned from `initialize` and surfaced to the model as an MCP instructions block |
240240| `options.tools` | `Array<SdkMcpToolDefinition>` | Array of tool definitions created with [`tool()`](#tool) |
241| `options.alwaysLoad` | `boolean` | When `true`, every tool from this server stays in the initial prompt instead of being deferred behind [tool search](/docs/en/agent-sdk/tool-search). Combines with per-tool `alwaysLoad` in [`tool()`](#tool) |
241| `options.alwaysLoad` | `boolean` | When `true`, this server's tools stay in the initial prompt instead of being deferred behind [tool search](/docs/en/agent-sdk/tool-search). Combines with per-tool `alwaysLoad` in [`tool()`](#tool) |
242242| `options.timeout` | `number` | Timeout in milliseconds for this server's tool calls. Claude Code applies it to this server in place of [`MCP_TOOL_TIMEOUT`](/docs/en/env-vars). Pass a whole number of at least 1000. Claude Code ignores other values. Requires TypeScript Agent SDK v0.3.248 or later |
243243
244244### `listSessions()`
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34873487
34883488Pass `"list"` to enumerate the user's published artifacts; only `limit` and `scope` may accompany it. `scope` defaults to `"mine"`, which lists artifacts the user owns; `"shared"` lists artifacts other people shared with the user, and `"all"` lists both.
34893489
3490`limit` sets the most artifacts a listing returns, from 1 to 200. A `limit` above 50 requires Agent SDK v0.3.292 or later. Without `limit`, a listing returns up to 25.
3491
34903492* `capabilities`: the runtime capabilities the published page uses, keyed by capability name, such as the [connectors the page may call](/docs/en/artifacts#pull-live-data-with-mcp-connectors). The artifact service validates the declaration and rejects a publish that names a capability the account can't use or gives one an invalid config. Pass `{}` to clear a stored declaration, and omit the field on a redeploy to keep it. Requires Agent SDK v0.3.235 or later.
34913493* `contract`: the runtime version the published page runs against. Omit it to keep the artifact's current version, pass `"latest"` to upgrade, or pass a specific version to pin or roll back. Requires Agent SDK v0.3.235 or later.
34923494
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44444446 rel?: "mine" | "shared";
44454447 }>;
44464448 truncated?: boolean;
4449 total?: number;
4450 total_at_least?: true;
44474451 scope?: "shared" | "all";
44484452 };
44494453```
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44514455Returns the published page's `url` and the local `path` that was published for the publish action, with `updated` set to true when the publish redeployed an existing artifact, and `warnings` carrying any publish-time advisories. The list action returns the `artifacts` rows instead, with `truncated` set when more artifacts exist than the requested limit. On listings whose scope isn't `"mine"`, each row carries `rel` marking whether the user owns the artifact or it was shared with them, and the output's `scope` records which non-default scope produced the listing; both are absent on default listings.
44524456
4457A list result also reports `total`, the number of artifacts that match the listed scope, including ones beyond `limit`. When `total_at_least` is set, that number is a lower bound and more artifacts may exist. Both fields require Agent SDK v0.3.292 or later.
4458
44534459### Projects
44544460
44554461**Tool name:** `Projects`
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53535359
53545360Emitted while Claude is producing a thinking block, including a redacted one. `estimated_tokens` is a running estimate of the thinking tokens generated so far in the current block, and `estimated_tokens_delta` is the increment carried by this frame. Use these estimates for progress display.
53555361
5356When the model or provider reports a breakdown, the final count for the top-level agent loop is the result message's [`usage.output_tokens_details.thinking_tokens`](#usage), which [doesn't include subagent tokens](/docs/en/agent-sdk/cost-tracking#get-the-total-cost-of-a-query).
5357
5358Requires Claude Code v2.1.153 or later.
5359
5360```typescript theme={null}
5361type SDKThinkingTokensMessage = {
5362 type: "system";
5363 subtype: "thinking_tokens";
5364 estimated_tokens: number;
5365 estimated_tokens_delta: number;
5366 user_message_uuid?: string;
5367 uuid: UUID;
5368 session_id: string;
5369};
5370```
5371
5372### `SDKSessionStateChangedMessage`
5373
5374Emitted when Claude Code reports the session's
5362When the model or provider reports a breakdown, the final count for the top-level agent loop is the result message's [`usage.output_tokens_details.thinking_tokens`](#usage), which
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