upload_file

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

With no annotations provided, the description carries the full transparency burden. It discloses that the file stays private, returns a file_id, and supports specific formats/size limits. While it doesn't discuss persistence or side effects, the information provided is sufficient for safe use of a basic upload operation.

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 front-loaded: the first sentence gives the core purpose, followed by useful context on privacy, reuse, and constraints. Every sentence adds necessary information with no filler.

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 a single parameter, no output schema, and no annotations, the description fully covers purpose, return value, privacy, supported formats, size limit, and downstream usage. It is complete and self-sufficient.

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?

The input schema already covers file_path with a clear description (100% coverage). The description adds value by specifying allowed file types and the 48 MB limit, which gives the agent practical constraints beyond the raw schema.

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 action ('Upload a local image or video file'), the target resource ('xAI Files API'), and the primary output ('get a file_id'). It also distinguishes itself from sibling tools (generate_video, edit_video, extend_video) by positioning the file_id as reusable input for those 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 explains when to use it ('reusing the same asset across multiple calls without re-uploading') and specifies constraints (supported formats, max size). It does not explicitly state when not to use it or mention alternative methods, but the context is clear enough for a simple upload tool.

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