Attach a file (PDF, snapshot) to an item

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

Annotations (readOnlyHint=false, openWorldHint=true) align with the description's 'Add' action. The description adds extra behavioral context: the file is 'stored', meaning it persists; the URL is downloaded first; filename/content_type inference; and the return of a new attachment key. It also mentions the potential permission prompt. While not exhaustive (e.g., what happens if both path and url are provided is not specified), it provides meaningful beyond-annotation details.

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

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

The description is concise and well-structured: three sentences. It front-loads the core purpose, then explains required parameters, then optional parameters and environment context, and finally the return value. Every sentence contributes useful information without redundancy or fluff.

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

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

For a tool with 6 parameters and no output schema, the description covers all essential aspects: what the tool does, how to specify the file (path or url), inference rules for optional parameters, environment requirements (Zotero 10+), permission handling, and the return value (new attachment key). It is sufficiently complete for an agent to invoke correctly.

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

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

Schema description coverage is 100%, but the description adds value beyond the schema: it clarifies that 'parent' is an item key, 'path' must be readable by the Zoteus process, 'url' is downloaded first, and 'filename' and 'content_type' are inferred when omitted (with a concrete example for content_type: pdf -> application/pdf). This enhances the agent's understanding of parameter semantics.

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

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

The description clearly states the tool's purpose: 'Add a stored file attachment (e.g. a PDF full text) under an existing item.' It identifies the specific verb (attach), resource (file attachment), and the target (existing item). It distinguishes from sibling tools by specifying 'stored file attachment' and the need for a parent item key, setting it apart from general item creation or management tools.

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

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

The description provides explicit guidance: 'Give `parent` (the item key) and either `path` (a local file the Zoteus process can read) or `url` (downloaded first).' It also explains that `filename` and `content_type` are inferred when omitted, and notes the requirement for Zotero 10+ and a one-time write permission prompt. This tells the agent exactly when and how to use it, including prerequisites and alternatives.

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