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advisor-tool changedagents-and-tools/tool-use/advisor-tool

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Recorded here 13 Oct 2026 23:07 UTC

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Lines−51removed

From line 60 where the diff opens

First seen 14 Aug 2026 this site's first read of the page

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from line 60, old and new numbered

lines

from line 60

6060 {

6161 "type": "advisor_20260301",

6262 "name": "advisor",

63 "model": "claude-opus-5"

63 "model": "claude-opus-5-5"

6464 }

6565 ],

6666 "messages": [{

from line 77

7777 tools:

7878 - type: advisor_20260301

7979 name: advisor

80 model: claude-opus-5

80 model: claude-opus-5-5

8181 messages:

8282 - role: user

8383 content: Build a concurrent worker pool in Go with graceful shutdown.

from line 95

9595 {

9696 "type": "advisor_20260301",

9797 "name": "advisor",

98 "model": "claude-opus-5",

98 "model": "claude-opus-5-5",

9999 }

100100 ],

101101 messages=[

from line 120

120120 {

121121 type: "advisor_20260301",

122122 name: "advisor",

123 model: "claude-opus-5"

123 model: "claude-opus-5-5"

124124 }

125125 ],

126126 messages: [

from line 148

148148 {

149149 new BetaAdvisorTool20260301

150150 {

151 Model = Messages::Model.ClaudeOpus5

151 Model = Messages::Model.ClaudeOpus5_5

152152 }

153153 },

154154 Messages =

from line 174

174174 MaxTokens: 4096,

175175 Tools: []anthropic.BetaToolUnionParam{

176176 {OfAdvisorTool20260301: &anthropic.BetaAdvisorTool20260301Param{

177 Model: anthropic.ModelClaudeOpus5,

177 Model: anthropic.ModelClaudeOpus5_5,

178178 }},

179179 },

180180 Messages: []anthropic.BetaMessageParam{

from line 203

203203 .model(Model.CLAUDE_SONNET_5)

204204 .maxTokens(4096L)

205205 .addTool(BetaAdvisorTool20260301.builder()

206 .model(Model.CLAUDE_OPUS_5)

206 .model(Model.CLAUDE_OPUS_5_5)

207207 .build())

208208 .addUserMessage("Build a concurrent worker pool in Go with graceful shutdown.")

209209 .addBeta("advisor-tool-2026-03-01")

from line 230

230230 [

231231 'type' => 'advisor_20260301',

232232 'name' => 'advisor',

233 'model' => 'claude-opus-5',

233 'model' => 'claude-opus-5-5',

234234 ],

235235 ],

236236 betas: ['advisor-tool-2026-03-01'],

from line 249

249249 {

250250 type: "advisor_20260301",

251251 name: "advisor",

252 model: "claude-opus-5"

252 model: "claude-opus-5-5"

253253 }

254254 ],

255255 messages: [

from line 265

265265 ```

266266</CodeGroup>

267267

268The response `content` includes an `advisor_tool_result` block carrying the advisor's guidance. With `claude-opus-5` as the advisor, as in this quick start, the block's `content` field is an `advisor_redacted_result` variant (encrypted; the executor reads it server-side, but your client does not). To see the advice text directly in your response, use `claude-opus-4-8` as the advisor model instead, which returns the plaintext `advisor_result` variant. See [Result variants](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#result-variants) for both shapes side by side and which advisor models return which, and [Model compatibility](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#model-compatibility) for the full list of valid pairs.

268The response `content` includes an `advisor_tool_result` block carrying the advisor's guidance. With `claude-opus-5-5` as the advisor, as in this quick start, the block's `content` field is an `advisor_redacted_result` variant (encrypted; the executor reads it server-side, but your client does not). To see the advice text directly in your response, use `claude-opus-4-8` as the advisor model instead, which returns the plaintext `advisor_result` variant. See [Result variants](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#result-variants) for both shapes side by side and which advisor models return which, and [Model compatibility](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#model-compatibility) for the full list of valid pairs.

269269

270270## How it works

271271

from line 286

286286| ------------ | -------------- | -------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

290290| `max_uses` | integer | unlimited | Maximum number of advisor calls allowed in a single request. Once the executor reaches this cap, further advisor calls return an `advisor_tool_result_error` with `error_code: "max_uses_exceeded"` and the executor continues without further advice. This is a per-request cap, not a per-conversation cap. See [Cost control](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#cost-control) for conversation-level limits. |

291291| `max_tokens` | integer | advisor model's output cap | Caps the advisor's total output (thinking plus text) per call. Minimum 1024. See [Capping advisor output](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#capping-advisor-output). |

292292| `caching` | object \| null | `null` (off) | Enables [prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching) for the advisor's own transcript across calls within a conversation. See [Advisor prompt caching](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#advisor-prompt-caching). |

from line 299

299299

300300### Successful advisor call

301301

302When the advisor is called, a `server_tool_use` block is followed by an `advisor_tool_result` block in the assistant's content. The following example shows the plaintext `advisor_result` variant returned by a Claude Opus 4.8 advisor. The [Quick start](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#quick-start) uses Claude Opus 5, which returns the encrypted `advisor_redacted_result` variant instead; see [Result variants](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#result-variants) for both shapes side by side.

302When the advisor is called, a `server_tool_use` block is followed by an `advisor_tool_result` block in the assistant's content. The following example shows the plaintext `advisor_result` variant returned by a Claude Opus 4.8 advisor. The [Quick start](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#quick-start) uses Claude Opus 5.5, which returns the encrypted `advisor_redacted_result` variant instead; see [Result variants](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#result-variants) for both shapes side by side.

303303

304304```json

305305{

from line 361

361361}

362362```

363363

364With `"model": "claude-opus-5"`, the advice is encrypted:

364With `"model": "claude-opus-5-5"`, the advice is encrypted:

365365

366366```json

367367{

from line 411

411411

412412## Multi-turn conversations

413413

414Pass the full assistant content, including `advisor_tool_result` blocks, back to the API on subsequent turns. Round-trip the result blocks verbatim: with a Claude Opus 5 advisor the result block's `content` is the encrypted `advisor_redacted_result` variant, and the server decrypts it and renders the advice into the executor's prompt on the next turn (see [Result variants](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#result-variants)). The mechanics are identical for any advisor model.

414Pass the full assistant content, including `advisor_tool_result` blocks, back to the API on subsequent turns. Round-trip the result blocks verbatim: with a Claude Opus 5.5 advisor the result block's `content` is the encrypted `advisor_redacted_result` variant, and the server decrypts it and renders the advice into the executor's prompt on the next turn (see [Result variants](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#result-variants)). The mechanics are identical for any advisor model.

415415

416416<CodeGroup exclude="shell">

417417 ```python Python

from line 421

421421 {

422422 "type": "advisor_20260301",

423423 "name": "advisor",

424 "model": "claude-opus-5",

424 "model": "claude-opus-5-5",

425425 }

426426 ]

427427

from line 462

462462 {

463463 type: "advisor_20260301",

464464 name: "advisor",

465 model: "claude-opus-5"

465 model: "claude-opus-5-5"

466466 }

467467 ];

468468

from line 500

500500 using Anthropic.Models.Beta.Messages;

501501 using Messages = Anthropic.Models.Messages;

502502

503 var client = new AnthropicClient();

503 // Advisor calls run a second model inside the request, so allow more than the

504 // C# SDK's default non-streaming timeout, which it sizes from max_tokens.

505 var client = new AnthropicClient { Timeout = TimeSpan.FromMinutes(5) };

504506

505507 var tools = new BetaToolUnion[]

506508 {

507 new BetaAdvisorTool20260301 { Model = Messages::Model.ClaudeOpus5 }

509 new BetaAdvisorTool20260301 { Model = Messages::Model.ClaudeOpus5_5 }

508510 };

509511

510512 var messages = new List<BetaMessageParam>

from line 548

546548

547549 tools := []anthropic.BetaToolUnionParam{

548550 {OfAdvisorTool20260301: &anthropic.BetaAdvisorTool20260301Param{

549 Model: anthropic.ModelClaudeOpus5,

551 Model: anthropic.ModelClaudeOpus5_5,

550552 }},

551553 }

552554

from line 603

601603

602604 List<BetaToolUnion> tools = List.of(

603605 BetaToolUnion.ofAdvisorTool20260301(

604 BetaAdvisorTool20260301.builder().model(Model.CLAUDE_OPUS_5).build()));

606 BetaAdvisorTool20260301.builder().model(Model.CLAUDE_OPUS_5_5).build()));

605607

606608 List<BetaMessageParam> messages = new ArrayList<>();

607609 messages.add(BetaMessageParam.builder()

from line 649

647649 [

648650 'type' => 'advisor_20260301',

649651 'name' => 'advisor',

650 'model' => 'claude-opus-5',

652 'model' => 'claude-opus-5-5',

651653 ],

652654 ];

653655

from line 690

688690 {

689691 type: "advisor_20260301",

690692 name: "advisor",

691 model: "claude-opus-5"

693 model: "claude-opus-5-5"

692694 }

693695 ]

694696

from line 768

766768

767769

768770 tools = [

769 {"type": "advisor_20260301", "name": "advisor", "model": "claude-opus-5"},

771 {

772 "type": "advisor_20260301",

773 "name": "advisor",

774 "model": "claude-opus-5-5",

775 },

770776 # ... your other tools

771777 ]

772778 task = "Build a concurrent worker pool in Go with graceful shutdown."

from line 829

823829 }

824830

825831 const tools: Anthropic.Beta.Messages.BetaToolUnion[] = [

826 { type: "advisor_20260301", name: "advisor", model: "claude-opus-5" }

832 { type: "advisor_20260301", name: "advisor", model: "claude-opus-5-5" }

827833 // ... your other tools

828834 ];

829835 const task = "Build a concurrent worker pool in Go with graceful shutdown.";

from line 901

895901

896902 var tools = new BetaToolUnion[]

897903 {

898 new BetaAdvisorTool20260301 { Model = Messages::Model.ClaudeOpus5 }

904 new BetaAdvisorTool20260301 { Model = Messages::Model.ClaudeOpus5_5 }

899905 // ... your other tools

900906 };

901907 var task = "Build a concurrent worker pool in Go with graceful shutdown.";

from line 976

970976

971977 tools := []anthropic.BetaToolUnionParam{

972978 {OfAdvisorTool20260301: &anthropic.BetaAdvisorTool20260301Param{

973 Model: anthropic.ModelClaudeOpus5,

979 Model: anthropic.ModelClaudeOpus5_5,

974980 }},

975981 // ... your other tools

976982 }

from line 1069

10631069

10641070 List<BetaToolUnion> tools = List.of(

10651071 BetaToolUnion.ofAdvisorTool20260301(

1066 BetaAdvisorTool20260301.builder().model(Model.CLAUDE_OPUS_5).build())

1072 BetaAdvisorTool20260301.builder().model(Model.CLAUDE_OPUS_5_5).build())

10671073 // ... your other tools

10681074 );

10691075 String task = "Build a concurrent worker pool in Go with graceful shutdown.";

from line 1149

11431149 }

11441150

11451151 $tools = [

1146 ['type' => 'advisor_20260301', 'name' => 'advisor', 'model' => 'claude-opus-5'],

1152 ['type' => 'advisor_20260301', 'name' => 'advisor', 'model' => 'claude-opus-5-5'],

11471153 // ... your other tools

11481154 ];

11491155 $task = 'Build a concurrent worker pool in Go with graceful shutdown.';

from line 1207

12011207 end

12021208

12031209 tools = [

1204 { type: "advisor_20260301", name: "advisor", model: "claude-opus-5" }

1210 { type: "advisor_20260301", name: "advisor", model: "claude-opus-5-5" }

12051211 # ... your other tools

12061212 ]

12071213 task = "Build a concurrent worker pool in Go with graceful shutdown."

from line 1278

12721278 },

12731279 {

12741280 "type": "advisor_message",

1275 "model": "claude-opus-5",

1281 "model": "claude-opus-5-5",

12761282 "input_tokens": 823,

12771283 "cache_read_input_tokens": 0,

12781284 "cache_creation_input_tokens": 0,

from line 1324

13181324 {

13191325 "type": "advisor_20260301",

13201326 "name": "advisor",

1321 "model": "claude-opus-5",

1327 "model": "claude-opus-5-5",

13221328 "caching": {"type": "ephemeral", "ttl": "5m"},

13231329 }

13241330 ]

from line 1335

13291335 {

13301336 type: "advisor_20260301",

13311337 name: "advisor",

1332 model: "claude-opus-5",

1338 model: "claude-opus-5-5",

13331339 caching: { type: "ephemeral", ttl: "5m" }

13341340 }

13351341 ];

from line 1349

13431349 {

13441350 new BetaAdvisorTool20260301

13451351 {

1346 Model = Messages::Model.ClaudeOpus5,

1352 Model = Messages::Model.ClaudeOpus5_5,

13471353 Caching = new BetaCacheControlEphemeral { Ttl = Ttl.Ttl5m }

13481354 }

13491355 };

from line 1358

13521358 ```go Go

13531359 tools := []anthropic.BetaToolUnionParam{

13541360 {OfAdvisorTool20260301: &anthropic.BetaAdvisorTool20260301Param{

1355 Model: anthropic.ModelClaudeOpus5,

1361 Model: anthropic.ModelClaudeOpus5_5,

13561362 Caching: anthropic.BetaCacheControlEphemeralParam{TTL: anthropic.BetaCacheControlEphemeralTTLTTL5m},

13571363 }},

13581364 }

from line 1372

13661372

13671373 List<BetaToolUnion> tools = List.of(

13681374 BetaToolUnion.ofAdvisorTool20260301(BetaAdvisorTool20260301.builder()

1369 .model(Model.CLAUDE_OPUS_5)

1375 .model(Model.CLAUDE_OPUS_5_5)

13701376 .caching(BetaCacheControlEphemeral.builder()

13711377 .ttl(BetaCacheControlEphemeral.Ttl.TTL_5M)

13721378 .build())

from line 1384

13781384 [

13791385 'type' => 'advisor_20260301',

13801386 'name' => 'advisor',

1381 'model' => 'claude-opus-5',

1387 'model' => 'claude-opus-5-5',

13821388 'caching' => ['type' => 'ephemeral', 'ttl' => '5m'],

13831389 ],

13841390 ];

from line 1395

13891395 {

13901396 type: "advisor_20260301",

13911397 name: "advisor",

1392 model: "claude-opus-5",

1398 model: "claude-opus-5-5",

13931399 caching: { type: "ephemeral", ttl: "5m" }

13941400 }

13951401 ]

from line 1427

14211427 {

14221428 "type": "advisor_20260301",

14231429 "name": "advisor",

1424 "model": "claude-opus-5",

1430 "model": "claude-opus-5-5",

14251431 },

14261432 {

14271433 "name": "run_bash",

from line 1450

14441450 {

14451451 type: "advisor_20260301",

14461452 name: "advisor",

1447 model: "claude-opus-5"

1453 model: "claude-opus-5-5"

14481454 },

14491455 {

14501456 name: "run_bash",

from line 1471

14651471 var tools = new BetaToolUnion[]

14661472 {

14671473 new BetaWebSearchTool20250305 { MaxUses = 5 },

1468 new BetaAdvisorTool20260301 { Model = Messages::Model.ClaudeOpus5 },

1474 new BetaAdvisorTool20260301 { Model = Messages::Model.ClaudeOpus5_5 },

14691475 new BetaTool

14701476 {

14711477 Name = "run_bash",

from line 1493

14871493 MaxUses: anthropic.Int(5),

14881494 }},

14891495 {OfAdvisorTool20260301: &anthropic.BetaAdvisorTool20260301Param{

1490 Model: anthropic.ModelClaudeOpus5,

1496 Model: anthropic.ModelClaudeOpus5_5,

14911497 }},

14921498 {OfTool: &anthropic.BetaToolParam{

14931499 Name: "run_bash",

from line 1520

15141520 .maxUses(5L)

15151521 .build()),

15161522 BetaToolUnion.ofAdvisorTool20260301(BetaAdvisorTool20260301.builder()

1517 .model(Model.CLAUDE_OPUS_5)

1523 .model(Model.CLAUDE_OPUS_5_5)

15181524 .build()),

15191525 BetaToolUnion.ofBetaTool(BetaTool.builder()

15201526 .name("run_bash")

from line 1542

15361542 [

15371543 'type' => 'advisor_20260301',

15381544 'name' => 'advisor',

1539 'model' => 'claude-opus-5',

1545 'model' => 'claude-opus-5-5',

15401546 ],

15411547 [

15421548 'name' => 'run_bash',

from line 1565

15591565 {

15601566 type: "advisor_20260301",

15611567 name: "advisor",

1562 model: "claude-opus-5"

1568 model: "claude-opus-5-5"

15631569 },

15641570 {

15651571 name: "run_bash",

from line 1697

16911697 {

16921698 "type": "advisor_20260301",

16931699 "name": "advisor",

1694 "model": "claude-opus-5",

1700 "model": "claude-opus-5-5",

16951701 "max_tokens": 2048,

16961702 }

16971703 ]

from line 1708

17021708 {

17031709 type: "advisor_20260301",

17041710 name: "advisor",

1705 model: "claude-opus-5",

1711 model: "claude-opus-5-5",

17061712 max_tokens: 2048

17071713 }

17081714 ];

from line 1722

17161722 {

17171723 new BetaAdvisorTool20260301

17181724 {

1719 Model = Messages::Model.ClaudeOpus5,

1725 Model = Messages::Model.ClaudeOpus5_5,

17201726 MaxTokens = 2048

17211727 }

17221728 };

from line 1731

17251731 ```go Go

17261732 tools := []anthropic.BetaToolUnionParam{

17271733 {OfAdvisorTool20260301: &anthropic.BetaAdvisorTool20260301Param{

1728 Model: anthropic.ModelClaudeOpus5,

1734 Model: anthropic.ModelClaudeOpus5_5,

17291735 MaxTokens: anthropic.Int(2048),

17301736 }},

17311737 }

from line 1744

17381744

17391745 List<BetaToolUnion> tools = List.of(

17401746 BetaToolUnion.ofAdvisorTool20260301(BetaAdvisorTool20260301.builder()

1741 .model(Model.CLAUDE_OPUS_5)

1747 .model(Model.CLAUDE_OPUS_5_5)

17421748 .maxTokens(2048L)

17431749 .build()));

17441750 ```

from line 1754

17481754 [

17491755 'type' => 'advisor_20260301',

17501756 'name' => 'advisor',

1751 'model' => 'claude-opus-5',

1757 'model' => 'claude-opus-5-5',

17521758 'max_tokens' => 2048,

17531759 ],

17541760 ];

from line 1765

17591765 {

17601766 type: "advisor_20260301",

17611767 name: "advisor",

1762 model: "claude-opus-5",

1768 model: "claude-opus-5-5",

17631769 max_tokens: 2048

17641770 }

17651771 ]

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