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What it does

Manage staged binary uploads for files too large for a single MCP tool call. Use action ‘start’ to begin an upload and get an upload ID, ‘append’ to send ordered base64 chunks, ‘complete’ to finalize and commit, or ‘cancel’ to discard. Workflow: start → append (×N) → complete.

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Required scope

files:write

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Parameters

ParameterTypeRequiredDescription
actionstringYesOperation to perform. Values: start, append, complete, cancel.
pathstringNoDestination file path within the workspace (for example ‘music/track.wav’). Required for ‘start’.
modestringNoUse ‘write’ to create-or-update, or ‘create’ to fail if the path already exists. Only used with ‘start’. Values: write, create.
expected_bytesintegerNoOptional final file size in raw bytes. If provided, ‘complete’ verifies it exactly. Only used with ‘start’.
mime_typestringNoOptional MIME type hint for the upload session (for example ‘audio/wav’). Only used with ‘start’.
upload_idstringNoUpload ID returned by the ‘start’ action. Required for ‘append’, ‘complete’, and ‘cancel’.
part_numberintegerNoZero-based chunk index. Send chunks in strict order: 0, 1, 2, … Required for ‘append’.
contentstringNoBase64-encoded chunk bytes. Keep each chunk under 1 MB (approx. 1.3 MB base64-encoded) to fit within standard MCP message limits. Use the size guidance from the ‘start’ response. Required for ‘append’.