What MCP can do, file type by file type

In one line: the full matrix — for every extension, what MCP can read, write whole, change only through a field-level tool, or not touch at all.

The axis changed

This page used to compare "a Writing Studio book" with "a Script Studio book". From 4.0 that question no longer holds: there is one writing studio, and a screenplay is a .script file in the file tree, one episode per file.

What decides what MCP can do is no longer which studio a book belongs to. It is what type of file you are touching.

The full matrix

Extension	Read	Whole-file write (write_file / edit_file / append_to_file)	How to change it
.md .markdown .txt	✅	✅	Write it
.map relationship map	✅	❌	update_relationship_map
.beats beat board	✅	❌	update_beat_board
.timeline timeline	✅	❌	update_timeline
.script screenplay	✅	❌	update_script
.geomap world map	✅	❌	update_world_map
.character .location	✅	❌	No AI route
.json .yaml .yml	✅	❌	No AI route
.png .jpg .jpeg .gif .pdf	✅	❌	No AI route
Anything else (.csv, no extension at all…)	✅	✅	Write it

That last row is deliberate. Authors keep all sorts of reference files, and refusing them to guard types nobody structured would break real work to prevent a hypothetical.

The authority is get_capabilities, not this table. It returns the contract this server actually enforces — see Guides and writing skills.

Three kinds of file, three behaviours

Prose (.md / .markdown / .txt). read_file, edit_file, write_file, create_file, append_to_file and delete_file all work. In practice, prefer edit_file: the author may be editing the same file, and an edit that cannot find its anchor fails loudly, where a whole-file write silently replaces what they just typed.

The five structured types. write_file, edit_file and append_to_file are all refused; changes go through one operation at a time. Two exceptions are worth remembering: create_file does work (but the content you send is ignored — the server writes an empty skeleton), and delete_file works too (deletion does not check the type policy, only the plan). Writing and deleting both belong to the subscription plans. See Structured editing tools.

Not writable at all. .character and .location have a format owned by Slima's own editors; .json and .yaml are configuration and data; media is media. Readable, not writable, and with no field-level alternative.

How the word count treats them

This follows from the type, and it is worth stating on its own:

• .md / .markdown / .txt — counted as prose
• .script — counted from the words inside its scenes, and it does feed the author's daily word count and streak
• .map / .beats / .timeline / .geomap — always zero

So an AI tidying up a relationship map leaves no fake progress on the author's numbers.

Tools that do not care about file type

A whole set of tools work on the book rather than a file, and the table above does not apply to them: list_books, get_book, get_book_structure, get_writing_stats, search_content, semantic_search, notes, comments, and the teaching set.

Some of them do behave differently on some files — see Tools that behave differently on some files.

create_book only makes writing books

Anything MCP creates is a Writing Studio book. The older Script Studio is no longer taking new works, so there was nothing to create there anyway. Writing a screenplay in 4.0 starts inside a book: right-click in the file tree, New screenplay, and you get a .script file.

If you still have an older Script Studio book

Those books still open, and MCP can still read them. They follow a separate rule set, which has nothing to do with the extension table above — it works on paths:

Action	Older Script Studio book
Read any file	✅ Including series.json, *.character, *.scene
Write / edit / delete	⚠️ Only under .script_studio/planning/
Structured files (series.json, season.json, episode.json, *.character, *.location, *.scene, *.storyline, *.note)	❌ Read-only over MCP
.script_studio/planning/.initialized	❌ Read-only (the frontend's bootstrap marker)
search_content	⚠️ Excludes those structured files by default; pass include_structured: true
analyze_chapter	❌ Not supported for these books at all

A write outside the allowed area returns 400 INVALID_PATH. For one book's exact rules, ask the book: read the resource slima://books/{book_token}/schema — see Query book schema with the resource.

get_book on such a book prints its write restrictions itself, which makes calling it the fastest way to check before doing anything.

Related

• Docs: Structured editing tools
• Docs: Structured-file protections
• Docs: Tools that behave differently on some files
• Docs: File operation tools
• Docs: Query book schema with the resource
• Docs: Manuscript vs reference