web-fetch-tool changedagents-and-tools/tool-use/web-fetch-tool
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14 Aug 2026
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from line 10
1010
1111The web fetch tool allows Claude to retrieve full content from specified web pages and PDF documents.
1212
13The latest web fetch tool version (`web_fetch_20260318`) supports **dynamic filtering**: Claude can write and execute code to filter fetched content before it reaches the context window, keeping only relevant information and discarding the rest. This reduces token consumption while maintaining response quality. Dynamic filtering is available with Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, [Claude Mythos Preview](https://anthropic.com/glasswing), Claude Opus 4.8, Claude Opus 4.7, Claude Opus 4.6, Claude Sonnet 5, and Claude Sonnet 4.6. `web_fetch_20260318` also adds [response inclusion](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool#response-inclusion) control for agentic workflows. The previous versions (`web_fetch_20260309` for dynamic filtering and [cache bypass](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool#cache-bypass), `web_fetch_20260209` for dynamic filtering only, `web_fetch_20250910` for basic fetch) remain available.
13The latest web fetch tool version (`web_fetch_20260318`) supports **dynamic filtering**: Claude can write and execute code to filter fetched content before it reaches the context window, keeping only relevant information and discarding the rest. This reduces token consumption while maintaining response quality. Dynamic filtering is available with Claude 4.6 and later models and [Claude Mythos Preview](https://anthropic.com/glasswing). `web_fetch_20260318` also adds [response inclusion](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool#response-inclusion) control for agentic workflows. The previous versions (`web_fetch_20260309` for dynamic filtering and [cache bypass](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool#cache-bypass), `web_fetch_20260209` for dynamic filtering only, `web_fetch_20250910` for basic fetch) remain available.
1414
1515Web fetch (with and without dynamic filtering) is available on the Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), and [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry). On Microsoft Foundry, deployments [hosted on Azure](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry#additional-features-not-supported-when-hosted-on-azure) support only the basic web fetch tool (`web_fetch_20250910`, without dynamic filtering). Deployments hosted on Anthropic support all versions. Web fetch is not currently available on Amazon Bedrock or Google Cloud.
1616
from line 88
8888 -H "anthropic-version: 2023-06-01" \
8989 -H "content-type: application/json" \
9090 -d '{
91 "model": "claude-opus-4-8",
91 "model": "claude-opus-5-5",
9292 "max_tokens": 4096,
9393 "messages": [
9494 {
from line 105
105105
106106 ```bash CLI
107107 ant messages create <<'YAML'
108 model: claude-opus-4-8
108 model: claude-opus-5-5
109109 max_tokens: 4096
110110 messages:
111111 - role: user
from line 122
122122 client = anthropic.Anthropic()
123123
124124 response = client.messages.create(
125 model="claude-opus-4-8",
125 model="claude-opus-5-5",
126126 max_tokens=4096,
127127 messages=[
128128 {
from line 139
139139 const client = new Anthropic();
140140
141141 const response = await client.messages.create({
142 model: "claude-opus-4-8",
142 model: "claude-opus-5-5",
143143 max_tokens: 4096,
144144 messages: [
145145 {
from line 159
159159
160160 var parameters = new MessageCreateParams
161161 {
162 Model = Model.ClaudeOpus4_8,
162 Model = Model.ClaudeOpus5_5,
163163 MaxTokens = 4096,
164164 Messages = [new() { Role = Role.User, Content = "Fetch the content at https://example.com/research-paper and extract the key findings." }],
165165 Tools = [new ToolUnion(new WebFetchTool20260318())]
from line 173
173173 client := anthropic.NewClient()
174174
175175 response, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
176 Model: anthropic.ModelClaudeOpus4_8,
176 Model: anthropic.ModelClaudeOpus5_5,
177177 MaxTokens: 4096,
178178 Messages: []anthropic.MessageParam{
179179 anthropic.NewUserMessage(anthropic.NewTextBlock("Fetch the content at https://example.com/research-paper and extract the key findings.")),
from line 195
195195 AnthropicClient client = AnthropicOkHttpClient.fromEnv();
196196
197197 MessageCreateParams params = MessageCreateParams.builder()
198 .model(Model.CLAUDE_OPUS_4_8)
198 .model(Model.CLAUDE_OPUS_5_5)
199199 .maxTokens(4096L)
200200 .addUserMessage("Fetch the content at https://example.com/research-paper and extract the key findings.")
201201 .addTool(WebFetchTool20260318.builder().build())
from line 214
214214 messages: [
215215 ['role' => 'user', 'content' => 'Fetch the content at https://example.com/research-paper and extract the key findings.']
216216 ],
217 model: 'claude-opus-4-8',
217 model: 'claude-opus-5-5',
218218 tools: [[
219219 'type' => 'web_fetch_20260318',
220220 'name' => 'web_fetch',
from line 227
227227 client = Anthropic::Client.new
228228
229229 message = client.messages.create(
230 model: "claude-opus-4-8",
230 model: "claude-opus-5-5",
231231 max_tokens: 4096,
232232 messages: [
233233 { role: "user", content: "Fetch the content at https://example.com/research-paper and extract the key findings." }
from line 252
252252 -H "anthropic-version: 2023-06-01" \
253253 -H "content-type: application/json" \
254254 -d '{
255 "model": "claude-opus-4-8",
255 "model": "claude-opus-5-5",
256256 "max_tokens": 1024,
257257 "messages": [
258258 {
from line 270
270270
271271 ```bash CLI
272272 ant messages create \
273 --model claude-opus-4-8 \
273 --model claude-opus-5-5 \
274274 --max-tokens 1024 \
275275 --message '{role: user, content: "Please analyze the content at https://example.com/article"}' \
276276 --tool '{type: web_fetch_20250910, name: web_fetch, max_uses: 5}'
from line 280
280280 client = anthropic.Anthropic()
281281
282282 response = client.messages.create(
283 model="claude-opus-4-8",
283 model="claude-opus-5-5",
284284 max_tokens=1024,
285285 messages=[
286286 {
from line 297
297297 const client = new Anthropic();
298298
299299 const response = await client.messages.create({
300 model: "claude-opus-4-8",
300 model: "claude-opus-5-5",
301301 max_tokens: 1024,
302302 messages: [
303303 {
from line 322
322322
323323 var parameters = new MessageCreateParams
324324 {
325 Model = Model.ClaudeOpus4_8,
325 Model = Model.ClaudeOpus5_5,
326326 MaxTokens = 1024,
327327 Messages = [new() { Role = Role.User, Content = "Please analyze the content at https://example.com/article" }],
328328 Tools = [new ToolUnion(new WebFetchTool20250910() { MaxUses = 5 })]
from line 336
336336 client := anthropic.NewClient()
337337
338338 response, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
339 Model: anthropic.ModelClaudeOpus4_8,
339 Model: anthropic.ModelClaudeOpus5_5,
340340 MaxTokens: 1024,
341341 Messages: []anthropic.MessageParam{
342342 anthropic.NewUserMessage(anthropic.NewTextBlock("Please analyze the content at https://example.com/article")),
from line 360
360360 AnthropicClient client = AnthropicOkHttpClient.fromEnv();
361361
362362 MessageCreateParams params = MessageCreateParams.builder()
363 .model(Model.CLAUDE_OPUS_4_8)
363 .model(Model.CLAUDE_OPUS_5_5)
364364 .maxTokens(1024L)
365365 .addUserMessage("Please analyze the content at https://example.com/article")
366366 .addTool(WebFetchTool20250910.builder()
from line 381
381381 messages: [
382382 ['role' => 'user', 'content' => 'Please analyze the content at https://example.com/article']
383383 ],
384 model: 'claude-opus-4-8',
384 model: 'claude-opus-5-5',
385385 tools: [[
386386 'type' => 'web_fetch_20250910',
387387 'name' => 'web_fetch',
from line 395
395395 client = Anthropic::Client.new
396396
397397 message = client.messages.create(
398 model: "claude-opus-4-8",
398 model: "claude-opus-5-5",
399399 max_tokens: 1024,
400400 messages: [
401401 { role: "user", content: "Please analyze the content at https://example.com/article" }
from line 667
667667 -H "anthropic-version: 2023-06-01" \
668668 -H "content-type: application/json" \
669669 -d '{
670 "model": "claude-opus-4-8",
670 "model": "claude-opus-5-5",
671671 "max_tokens": 4096,
672672 "messages": [
673673 {
from line 693
693693
694694 ```bash CLI
695695 ant messages create <<'YAML'
696 model: claude-opus-4-8
696 model: claude-opus-5-5
697697 max_tokens: 4096
698698 messages:
699699 - role: user
from line 716
716716 client = anthropic.Anthropic()
717717
718718 response = client.messages.create(
719 model="claude-opus-4-8",
719 model="claude-opus-5-5",
720720 max_tokens=4096,
721721 messages=[
722722 {
from line 741
741741 const client = new Anthropic();
742742
743743 const response = await client.messages.create({
744 model: "claude-opus-4-8",
744 model: "claude-opus-5-5",
745745 max_tokens: 4096,
746746 messages: [
747747 {
from line 769
769769
770770 var parameters = new MessageCreateParams
771771 {
772 Model = Model.ClaudeOpus4_8,
772 Model = Model.ClaudeOpus5_5,
773773 MaxTokens = 4096,
774774 Messages = [new() { Role = Role.User, Content = "Find recent articles about quantum computing and analyze the most relevant one in detail" }],
775775 Tools = [
from line 786
786786 client := anthropic.NewClient()
787787
788788 response, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
789 Model: anthropic.ModelClaudeOpus4_8,
789 Model: anthropic.ModelClaudeOpus5_5,
790790 MaxTokens: 4096,
791791 Messages: []anthropic.MessageParam{
792792 anthropic.NewUserMessage(anthropic.NewTextBlock("Find recent articles about quantum computing and analyze the most relevant one in detail")),
from line 817
817817 AnthropicClient client = AnthropicOkHttpClient.fromEnv();
818818
819819 MessageCreateParams params = MessageCreateParams.builder()
820 .model(Model.CLAUDE_OPUS_4_8)
820 .model(Model.CLAUDE_OPUS_5_5)
821821 .maxTokens(4096L)
822822 .addUserMessage("Find recent articles about quantum computing and analyze the most relevant one in detail")
823823 .addTool(WebSearchTool20250305.builder()
from line 842
842842 messages: [
843843 ['role' => 'user', 'content' => 'Find recent articles about quantum computing and analyze the most relevant one in detail']
844844 ],
845 model: 'claude-opus-4-8',
845 model: 'claude-opus-5-5',
846846 tools: [
847847 [
848848 'type' => 'web_search_20250305',
from line 864
864864 client = Anthropic::Client.new
865865
866866 message = client.messages.create(
867 model: "claude-opus-4-8",
867 model: "claude-opus-5-5",
868868 max_tokens: 4096,
869869 messages: [
870870 { role: "user", content: "Find recent articles about quantum computing and analyze the most relevant one in detail" }
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