> ## Documentation Index
> Fetch the complete documentation index at: https://modelcontextprotocol.io/llms.txt
> Use this file to discover all available pages before exploring further.

# File Uploads Charter

> Charter for the MCP File Uploads Working Group.

## Group Type

**Working Group**

## Mission Statement

The File Uploads Working Group exists to define how MCP tools and elicitation requests declare file
inputs so that hosts can present native file pickers and pass user-selected file content to servers.
Today, servers that need a file from the user resort to prose instructions asking for base64 strings
or local paths, which produces inconsistent UX and pushes encoding details onto end users. This WG
will specify a minimal, schema-level mechanism for declaring file inputs and the wire format for
delivering them, anchored on [SEP-2356](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2356).

## Scope

### In Scope

* **Specification Work**: SEPs defining declarative file input descriptors on tool input schemas and
  elicitation request schemas, the wire encoding for file content, and host-side handling
  requirements.
* **Reference Implementations**: SDK types and helpers for `FileInputDescriptor`, data URI encoding,
  and a sample host flow demonstrating picker invocation and value substitution.
* **Cross-Cutting Concerns**: Coordination with the MCP Apps WG where embedded UI surfaces present
  their own file pickers, and with the Security WG on host-side validation requirements.
* **Documentation**: Specification sections covering file input declaration and a migration guide
  for servers currently using ad-hoc base64 instructions.

### Out of Scope

* Server-to-client file delivery, which is already covered by Resources and `BlobResourceContents`.
* Changes to the transport layer or session model.

The WG may evaluate approaches such as streaming, chunked transfer, or presigned upload URLs as part
of its design work; whether those land in the initial SEP or a follow-up is a WG decision rather
than a charter constraint.

### Related Groups

* **MCP Apps WG** — embedded app UIs may surface their own file pickers; the descriptor format
  should be reusable in that context.
* **Security WG** — host-side validation requirements for user-supplied file content (the SEP
  references [OWASP ASVS V5](https://owasp.org/www-project-application-security-verification-standard/)
  for general upload hygiene).
* **Tool Annotations IG** — file input descriptors are a form of input-parameter metadata and should
  remain consistent with the broader annotation taxonomy.

## Leadership

| Role | Name           | Organization | GitHub                                   | Term    |
| ---- | -------------- | ------------ | ---------------------------------------- | ------- |
| Lead | Den Delimarsky | Anthropic    | [@localden](https://github.com/localden) | Initial |

Sponsored by Den Delimarsky ([@localden](https://github.com/localden)) and Nick Cooper
([@nickcoai](https://github.com/nickcoai)).

## Authority & Decision Rights

| Decision Type                       | Authority Level                                        |
| ----------------------------------- | ------------------------------------------------------ |
| Meeting logistics & scheduling      | WG Leads (autonomous)                                  |
| Proposal prioritization within WG   | WG Leads (autonomous)                                  |
| SEP triage & closure (in scope)     | WG Leads (autonomous, with documented rationale)       |
| Technical design within scope       | WG consensus                                           |
| Spec changes (additive)             | WG consensus → Core Maintainer approval                |
| Spec changes (breaking/fundamental) | WG consensus → Core Maintainer approval + wider review |
| Scope expansion                     | Core Maintainer approval required                      |
| WG Member approval                  | WG Member sponsors                                     |

## Membership

| Name           | Organization | GitHub                                   | Discord | Level     |
| -------------- | ------------ | ---------------------------------------- | ------- | --------- |
| Den Delimarsky | Anthropic    | [@localden](https://github.com/localden) |         | Lead      |
| Nick Cooper    | OpenAI       | [@nickcoai](https://github.com/nickcoai) |         | WG Member |
| Olivier Chafik | Anthropic    | [@ochafik](https://github.com/ochafik)   |         | WG Member |

## Operations

| Meeting         | Frequency | Duration | Purpose                               |
| --------------- | --------- | -------- | ------------------------------------- |
| Working Session | Biweekly  | 30 min   | Technical discussion, proposal review |

Discord: `#file-uploads-wg`

## Deliverables & Success Metrics

### Active Work Items

| Item                                                                                                        | Status | Target Date | Champion                               |
| ----------------------------------------------------------------------------------------------------------- | ------ | ----------- | -------------------------------------- |
| [SEP-2356: Declarative file inputs](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2356) | Draft  | End May     | [@ochafik](https://github.com/ochafik) |
| TypeScript SDK reference implementation                                                                     | —      | End May     | [@ochafik](https://github.com/ochafik) |
| Reference implementation in a second Tier-1 SDK                                                             | —      | End June    | TBD                                    |

### Success Criteria

* An accepted SEP defining the file input descriptor and wire encoding.
* Reference implementations in at least two Tier-1 SDKs.
* At least one production host rendering a native file picker from the descriptor.
* Conformance test coverage for the new schema keyword.

## Changelog

| Date       | Change          |
| ---------- | --------------- |
| 2026-04-23 | Initial charter |