Agent Skills: docx and pptx skills fail silently with streaming

[tarik0]

Description

When using the Agent Skills beta with the container.skills parameter, the docx and pptx skills cause the stream to end without producing a Message. The pdf and xlsx skills work correctly.

Environment

• SDK: @anthropic-ai/sdk (latest)
• Model: claude-sonnet-4-5-20250929
• Beta headers: code-execution-2025-08-25,skills-2025-10-02

Reproduction

import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic();

// ✅ This works
const working = client.messages.stream({
  model: 'claude-sonnet-4-5-20250929',
  max_tokens: 4096,
  container: {
    skills: [{ type: 'anthropic', skill_id: 'pdf', version: 'latest' }]
  },
  tools: [{ type: 'code_execution_20250825', name: 'code_execution' }],
  messages: [{ role: 'user', content: 'Hello' }]
}, {
  headers: { 'anthropic-beta': 'code-execution-2025-08-25,skills-2025-10-02' }
});

// ❌ This fails
const failing = client.messages.stream({
  model: 'claude-sonnet-4-5-20250929',
  max_tokens: 4096,
  container: {
    skills: [{ type: 'anthropic', skill_id: 'docx', version: 'latest' }]
  },
  tools: [{ type: 'code_execution_20250825', name: 'code_execution' }],
  messages: [{ role: 'user', content: 'Hello' }]
}, {
  headers: { 'anthropic-beta': 'code-execution-2025-08-25,skills-2025-10-02' }
});

Test Results

Skill	Status
pdf	✅ Works
xlsx	✅ Works
docx	❌ Fails
pptx	❌ Fails

Error

Stream ends with: stream ended without producing a Message with role=assistant

Expected

All documented skills should work per the Skills Guide.

[tarik0]

Example PoC

import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic({
  apiKey: process.env.ANTHROPIC_API_KEY
});

async function testSkill(skillId) {
  console.log(`\nTesting skill: ${skillId}`);
  try {
    const stream = client.messages.stream({
      model: 'claude-sonnet-4-5-20250929',
      max_tokens: 1024,
      container: {
        skills: [{ type: 'anthropic', skill_id: skillId, version: 'latest' }]
      },
      tools: [{ type: 'code_execution_20250825', name: 'code_execution' }],
      messages: [{ role: 'user', content: 'Hello, respond briefly.' }]
    }, {
      headers: { 'anthropic-beta': 'code-execution-2025-08-25,skills-2025-10-02' }
    });
    
    const message = await stream.finalMessage();
    console.log(`✅ ${skillId}: SUCCESS`);
    return true;
  } catch (error) {
    console.log(`❌ ${skillId}: FAILED - ${error.message}`);
    return false;
  }
}

console.log('=== Agent Skills Test ===');
await testSkill('pdf');
await testSkill('xlsx');
await testSkill('docx');
await testSkill('pptx');
console.log('\n=== Test Complete ===');

Output

=== Agent Skills Test ===                                                                   
                                                                                              
  Testing skill: pdf                                                                          
  ✅ pdf: SUCCESS                                                                             
                                                                                              
  Testing skill: xlsx                                                                         
  ✅ xlsx: SUCCESS                                                                            
                                                                                              
  Testing skill: docx                                                                         
  ❌ docx: FAILED - stream ended without producing a Message with role=assistant              
                                                                                              
  Testing skill: pptx                                                                         
  ❌ pptx: FAILED - stream ended without producing a Message with role=assistant 

[yuniet87]

Same error here... They were working without problems until yesterday.

[ironwill9698]

Same issue - pptx skill is failing

[tarik0]

Additional Testing: Official Docs Method vs Streaming

I ran additional tests comparing both the official docs method (client.beta.messages.create()) and streaming (client.beta.messages.stream()) using the proper betas array parameter.

Key Finding

The create() method exposes the actual error: 500 Internal Server Error

While streaming silently fails, the non-streaming method returns an explicit server error, confirming this is an API-side issue.

---

Test Code

import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic({
  apiKey: process.env.ANTHROPIC_API_KEY
});

// Official docs method (client.beta.messages.create)
async function testSkillCreate(skillId) {
  const response = await client.beta.messages.create({
    model: 'claude-haiku-4-5-20251001',
    max_tokens: 4096,
    betas: ['code-execution-2025-08-25', 'skills-2025-10-02'],
    container: {
      skills: [{ type: 'anthropic', skill_id: skillId, version: 'latest' }]
    },
    tools: [{ type: 'code_execution_20250825', name: 'code_execution' }],
    messages: [{ role: 'user', content: 'Hello, respond briefly.' }]
  });
}

// Streaming method (client.beta.messages.stream)
async function testSkillStream(skillId) {
  const stream = client.beta.messages.stream({
    model: 'claude-haiku-4-5-20251001',
    max_tokens: 4096,
    betas: ['code-execution-2025-08-25', 'skills-2025-10-02'],
    container: {
      skills: [{ type: 'anthropic', skill_id: skillId, version: 'latest' }]
    },
    tools: [{ type: 'code_execution_20250825', name: 'code_execution' }],
    messages: [{ role: 'user', content: 'Hello, respond briefly.' }]
  });
  await stream.finalMessage();
}

---

Results (2026-02-01)

Official Docs Method: client.beta.messages.create()

Testing skill (create): pdf
✅ pdf (create): SUCCESS

Testing skill (create): xlsx
✅ xlsx (create): SUCCESS

Testing skill (create): docx
❌ docx (create): FAILED - 500 {"type":"error","error":{"type":"api_error","message":"Internal server error"}}

Testing skill (create): pptx
❌ pptx (create): FAILED - 500 {"type":"error","error":{"type":"api_error","message":"Internal server error"}}

Streaming Method: client.beta.messages.stream()

Testing skill (stream): pdf
✅ pdf (stream): SUCCESS

Testing skill (stream): xlsx
✅ xlsx (stream): SUCCESS

Testing skill (stream): docx
❌ docx (stream): FAILED - stream ended without producing a Message with role=assistant

Testing skill (stream): pptx
❌ pptx (stream): FAILED - stream ended without producing a Message with role=assistant

---

Summary

Skill	create()	stream()
pdf	✅ SUCCESS	✅ SUCCESS
xlsx	✅ SUCCESS	✅ SUCCESS
docx	❌ 500 Internal Server Error	❌ Stream dies silently
pptx	❌ 500 Internal Server Error	❌ Stream dies silently

Conclusion: The API returns 500 Internal Server Error for docx and pptx skills. This happens with both the official client.beta.messages.create() method and streaming, confirming it's a server-side issue—not an SDK or implementation problem.

[DevLeti]

Same error here.

[somya-aida]

another thread for the same @samj-anthropic