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Sweep 27 Oct 2026 · 19:04Z Build v2.1.312 531 read Stable v2.1.308 Latest v2.1.312 Next v2.1.312 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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token-counting changedbuild-with-claude/token-counting

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First seen 14 Aug 2026 this site's first read of the page
Recorded edits21to this page, all time

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2727 
2828The [token counting](https://platform.claude.com/docs/en/api/messages/count_tokens) endpoint accepts the same structured list of inputs for creating a message, including support for system prompts, [tools](https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview), [images](https://platform.claude.com/docs/en/build-with-claude/vision), and [PDFs](https://platform.claude.com/docs/en/build-with-claude/pdf-support). The response contains the total number of input tokens.
2929 
30This endpoint returns an `invalid_request_error` for a few inputs that the Messages API accepts: [server tools](https://platform.claude.com/docs/en/agents-and-tools/tool-use/server-tools) such as web search, web fetch, code execution, and tool search (every server tool except the [advisor tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool)), the [MCP connector](https://platform.claude.com/docs/en/agents-and-tools/mcp-connector), and `image` or `document` blocks with a `url` or `file` source. Send images and PDFs as base64 to count them. For requests that use server tools or MCP servers, the Messages API response reports the tokens used in its `usage` object.
30This endpoint returns an `invalid_request_error` for a few inputs that the Messages API accepts:
3131 
32* [Server tools](https://platform.claude.com/docs/en/agents-and-tools/tool-use/server-tools) such as web search, web fetch, code execution, and tool search (every server tool except the [advisor tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool))
33* The [MCP connector](https://platform.claude.com/docs/en/agents-and-tools/mcp-connector)
34* `image` or `document` blocks with a `url` or `file` source
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36Send images and PDFs as base64 to count them. For requests that use server tools or MCP servers, the Messages API response reports the tokens used in its `usage` object.
37 
3238<Note>
3339 The token count is an **estimate**. In some cases, the actual number of input tokens used when creating a message might differ by a small amount.
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from line 192
186192 ```
187193</CodeGroup>
188194 
189```text Output wrap
195```json Output
190196{ "input_tokens": 14 }
191197```
192198 
from line 475
469475 ```
470476</CodeGroup>
471477 
472```text Output wrap
478```json Output
473479{ "input_tokens": 403 }
474480```
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from line 784
778784 ```
779785</CodeGroup>
780786 
781```text Output wrap
787```json Output
782788{ "input_tokens": 1028 }
783789```
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from line 1109
11031109 ```
11041110</CodeGroup>
11051111 
1106```text Output wrap
1112```json Output
11071113{ "input_tokens": 88 }
11081114```
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from line 1395
13891395 ```
13901396</CodeGroup>
13911397 
1392```text Output wrap
1398```json Output
13931399{ "input_tokens": 2188 }
13941400```
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