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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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File Uploads Charter changedcommunity/working-groups/file-uploads

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Upstream edited this page at 26 Oct 2026 21:16 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 26 Oct 2026 21:37 UTC.

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1414or local paths, which produces inconsistent UX and pushes encoding details onto end users. This WG
1515will specify a minimal, schema-level mechanism for declaring file inputs and the wire format for
1616delivering them, anchored on [SEP-2356](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2356).
17As a secondary goal, the WG covers how a tool returns a file that is too large for a JSON-RPC message
18or that needs authorization to fetch.
1719 
1820## Scope
1921 
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2224* **Specification Work**: SEPs defining declarative file input descriptors on tool input schemas and
2325 elicitation request schemas, the wire encoding for file content, and host-side handling
2426 requirements.
27* **File Downloads (secondary)**: How a tool returns a file that is too large for a JSON-RPC message
28 or that needs authorization to fetch. Upload work takes priority.
2529* **Reference Implementations**: SDK types and helpers for `FileInputDescriptor`, data URI encoding,
2630 and a sample host flow demonstrating picker invocation and value substitution.
2731* **Cross-Cutting Concerns**: Coordination with the MCP Apps WG where embedded UI surfaces present
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3135 
3236### Out of Scope
3337 
34* Server-to-client file delivery, which is already covered by Resources and `BlobResourceContents`.
38* Server-to-client delivery of small files, which Resources and `BlobResourceContents` already cover.
3539* Changes to the transport layer or session model.
3640 
3741The WG may evaluate approaches such as streaming, chunked transfer, or presigned upload URLs as part
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108112| Date | Change |
109113| - | - |
110114| 2026-04-23 | Initial charter |
115| 2026-10-21 | Add file downloads to scope as a secondary item |
111116 
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