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Writes an artifact and, alongside it, the card that makes it findable — see Artifacts for how the two connect. Always writes to the org’s shared memory; there is no agent-scoped, private artifact. Three behaviours, selected by which arguments are present.

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Inline: content given

One call. For text up to 64KB — the only write path available to clients that speak MCP but cannot make an arbitrary HTTP request, such as ChatGPT connectors and Claude.ai custom connectors.

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Presigned upload: content omitted, mime_type and size_bytes given

For larger or binary content. Returns an upload URL rather than storing anything yet.
upload_url is signed for exactly the size_bytes you declared — an upload of any other size is rejected at the storage layer, so declare the real size. Upload the bytes with an HTTP PUT, then confirm.

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Confirm: artifact_id given

Call again with the artifact_id from the presigned response, no other arguments needed.
The server measures the uploaded object itself at confirm time — size and checksum both — and enforces the plan’s limits against that measured value, not the size_bytes you declared when requesting the URL. Confirm is what activates the artifact; nothing is discoverable through recall until it succeeds.

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Parameters

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string
required
Short name for the artifact. Up to 200 characters.
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string
required
One line describing what this is. Other agents find the artifact by this text, via the card — write it as the search phrase you would want to match. Up to 500 characters.
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'document' | 'record' | 'file'
required
document for prose, record for JSON, file for binary content.
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string
Inline text, up to 64KB. Omit to use the presigned upload path instead.
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string
MIME type of the upload. Required when content is omitted.
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integer
Byte size of the upload. Required when content is omitted — the upload URL is signed for exactly this many bytes.
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string
Optional space slug. Omit to file to the org’s default store.
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string
Optional project identifier. See Scope for how project resolution works.
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string
Id of an artifact this one replaces. The superseded version is retired and its card hidden, the same way a superseded memory stops surfacing in recall.
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string
Confirms an upload started earlier. Pass only this (and no other argument) to confirm.

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Limits

content over 64KB is rejected outright, with a message pointing at the presigned path — it does not silently truncate or fall back.
Both the inline and presigned paths are checked against the plan’s per-file limit and the org’s remaining pool before anything is stored. See storage limits.
A presigned upload is one HTTP PUT, so size_bytes above 100MB is rejected with too_large_for_single_upload. Multipart upload is not available yet, so an artifact larger than that cannot be stored in this release.This only affects plans whose per-file limit is above 100MB — on every other plan the plan limit is reached first and the error is file_too_large. Nothing is reserved when a request is refused.
A full pool rejects further artifact_put calls. It does not affect artifact_get or recall — existing artifacts stay readable.