upload_media

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

With no annotations, the description carries the full burden. It discloses supported file types and size limits (image 5MB, video 16MB, audio 16MB, document 100MB, sticker 500KB) and the return value (media ID). However, it does not mention permissions, rate limits, or error handling, though the provided information is substantial.

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?

Two sentences, front-loaded with the action and return, followed by a compact list of supported types and limits. No wasted words or redundancy.

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 straightforward upload tool with 3 well-described parameters and no output schema, the description adequately explains the return value and key constraints. It lacks some details like authentication or storage behavior, but for this complexity the information is 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?

Schema coverage is 100% with descriptive parameter definitions. The description adds meaningful context beyond the schema by specifying allowed file types and size limits, which informs the choice of mime_type and file_name. This goes beyond the baseline expected from high schema coverage.

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 media file to WhatsApp'), the resource ('a media file'), and the outcome ('Returns a media ID that can be used in messages'). This distinguishes it from sibling tools like get_media_info or delete_media, which operate on already-uploaded media.

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 implies the tool is used to obtain a media ID for later message sending, but it does not explicitly say when to use it versus alternatives (e.g., sending media directly via send_image_message). No exclusions or fallback conditions are provided.

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