io.github.54yyyu/zotero-mcp

zotero_attach_file

Attach a local file or PDF URL to an existing Zotero item via its item key, creating an imported child attachment. Use when the item is already in the library and you need to add the file.

Instructions

Attach a file to an EXISTING Zotero item as an imported child attachment (uploads the file bytes). Use when the item is already in the library and you have its key — e.g. attaching a PDF you found for a reference. To create a NEW item from a file, use zotero_add_from_file instead. item_key: key of the existing REGULAR item. Passing an attachment/note key fails with a hint to use its parent. file_path: ABSOLUTE local path (.pdf, .epub, .djvu, .doc, .docx, .odt, .rtf). url: direct http(s) link, downloaded server-side — PDF-only; for other formats download locally and use file_path. Exactly one of file_path/url must be given. filename: optional stored-filename override; defaults to the file's basename or the URL's last path segment (falling back to .pdf); a missing extension is appended automatically. Returns the created attachment's key. Idempotent: if the item already has an attachment with the same filename or identical content (MD5), nothing is re-uploaded. Requires a writable library (fails in local-only mode). Uploads count against the Zotero cloud storage quota unless WebDAV sync is configured. Run zotero_update_search_database afterwards to index the new file for semantic search. Example: zotero_attach_file(item_key='ABCD2345', file_path='/Users/me/smith-2020.pdf').

Input Schema

TableJSON Schema

Name	Required	Description	Default
`url`	No
`filename`	No
`item_key`	Yes
`file_path`	No

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 21, 2026

TDQS

A4.9/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Discloses idempotency, quota implications, writable library requirement, need for post-attachment database update, and file format restrictions. Also explains error handling for incorrect key types.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is somewhat lengthy but every sentence adds value. It is front-loaded with the core purpose and well-organized into logical segments. Minor redundancy could be trimmed, but overall efficient.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity (4 parameters, no nested objects, output schema present), the description covers all necessary context: usage, constraints, return value, side effects, and dependency on zotero_update_search_database.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 0% schema description coverage, the description thoroughly explains all four parameters: item_key (existing item, not attachment), file_path (absolute path with supported extensions), url (HTTP link, PDF-only), and filename (optional override with fallback). It also clarifies mutual exclusivity of file_path and url.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states it attaches a file to an existing Zotero item, using the verb 'attach' and specifying the resource. It distinguishes from the sibling tool zotero_add_from_file by noting that sibling creates a new item from a file.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit when-to-use ('item already in library'), what-not-to-do (passing attachment/note key), and an alternative tool (zotero_add_from_file for new items). Also includes examples and constraints.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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