Create a Message changedapi/beta/messages/create
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1616## Headers
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18- `"anthropic-version": optional string`
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20 The version of the Claude API you want to use.
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22 Read more about versioning and our version history [here](https://platform.claude.com/docs/en/api/versioning).
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1824- `"anthropic-beta": optional array of AnthropicBeta`
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2026 Optional header to specify the beta version(s) you want to use.
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7200 - `configs: optional map[BetaMCPToolConfig] or null`
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7202 Configuration overrides for specific tools, keyed by tool name
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7204 - `defer_loading: optional boolea
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