MCP App Store
by KeenEthics

Overview

Letter.md lets people read, search, and review Markdown documents from ChatGPT. It can create traceable comments and reviewable edit suggestions, inspect document images, compare versions, and open the complete realtime collaborative editor. With an explicit user request and publication permission, it can publish a document or update its public page; publishing never changes the private source document automatically. Users can also save generated Markdown as a new unpublished document in a writable Letter.md workspace or create a derivative document. Access is limited to the workspaces and scopes approved through OAuth.

Tools

complete_ai_request

ChatGPT
Complete a read-only in-editor AI workflow with concise structured results for the Letter.md UI.

create_agent_comment

ChatGPT
Add a traceable Codex comment anchored to a requested selection. This does not edit document content.

create_document

ChatGPT
Use this only when the user explicitly asks to save Markdown as a new Letter.md document. Creates a separate unpublished document in a writable workspace and never edits or overwrites an existing document. Identical retries are deduplicated automatically when idempotencyKey is omitted. For an active in-editor derivative workflow, use create_document_from_ai.

create_document_from_ai

ChatGPT
Use this only for an active in-editor derivative workflow. Creates a new Markdown document beside the source and never overwrites it. For an ordinary conversation save, use create_document.

create_review_findings

ChatGPT
Create categorized, anchored Codex findings as review comments. This never edits document content.

create_suggestion

ChatGPT
Create a reviewable suggestion. This never edits the document directly.

create_widget_comment

ChatGPT
Create a comment thread on the current selection in the mounted editor.

create_widget_realtime_ticket

ChatGPT
Create a short-lived, one-time realtime ticket for the mounted direct Letter.md widget.

decide_widget_suggestion

ChatGPT
Accept, reject, complete, cancel, or mark a pending editor suggestion as conflicted.

fail_ai_request

ChatGPT
Mark an in-editor AI request as failed when it cannot be completed safely or reliably.

get_document

ChatGPT
Read the latest Yjs-derived Markdown and block structure before creating suggestions.

get_document_asset

ChatGPT
Read one image referenced by the current document so its visual content can be reviewed.

get_document_assets_context

ChatGPT
List image assets referenced by a document for alt-text and caption review.

get_document_version_context

ChatGPT
Read the current document and one saved version for a read-only change summary.

get_edit_request_context

ChatGPT
Resolve an opaque request created in Letter.md into its primary document, frozen secondary sources, selection, and instruction context.

get_publication_context

ChatGPT
Read document content and existing publication metadata without publishing or changing it.

get_review_context

ChatGPT
Read the current Markdown together with unresolved comments for a traceable review task.

get_widget_image_asset

ChatGPT
Read one private image asset for the mounted Letter.md editor.

get_widget_image_document

ChatGPT
Read private image-document content for the mounted Letter.md editor.

heartbeat_ai_request

ChatGPT
Renew the current AI execution lease during a long-running in-editor request.

list_document_comments

ChatGPT
Read open or resolved review comments as context before creating a traceable suggestion.

list_document_create_destinations

ChatGPT
List only writable workspaces and their folder names so the user can choose where a new unpublished document will be created. Does not return document content or document metadata.

list_documents

ChatGPT
List the documents the linked user can access.

list_folders

ChatGPT
List the cloud folder tree for a workspace.

list_widget_comments

ChatGPT
Read open and resolved comment threads for the mounted Letter.md editor.

list_widget_suggestions

ChatGPT
Read pending suggestions for the mounted Letter.md editor.

list_workspaces

ChatGPT
List the workspaces the linked user can access.

publish_document

ChatGPT
Publish an unpublished document to the public web only after the user explicitly asks. Call get_publication_context first and pass its current document revision. Use update_document_publication when a public version already exists.

render_letter_editor

ChatGPT
Open the complete collaborative Markdown editor in the current MCP host, with realtime saving and reviewable Agent suggestions. Omit documentId to open the most recently updated accessible document.

reply_widget_comment

ChatGPT
Add a reply to an existing comment thread in the mounted editor.

search_workspace_documents

ChatGPT
Semantically search Markdown the linked user can access. Omit documentId and workspaceId to search every accessible workspace. Results contain short excerpts; use get_document for complete Markdown.

set_widget_comment_state

ChatGPT
Set an editor comment thread to open or resolved.

update_document_publication

ChatGPT
Replace an existing public version with the current document and metadata only after the user explicitly asks. Call get_publication_context first and pass both current revisions.

update_widget_image_document

ChatGPT
Save private image-document content from the mounted Letter.md editor.

upload_document_image

ChatGPT
Store a generated or supplied image in the document asset library. Pass raw base64 or a base64 data URL, then use the returned Markdown with create_suggestion for reviewable insertion.

Capabilities

WritesInteractive

Example Prompts

Click any prompt to copy it.

App Stats

35

Tools

3

Prompts

ChatGPT

Platforms

Works with

ChatGPT

Data refreshed daily