Upload media

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

The description goes far beyond the annotations by disclosing the two upload paths (simple vs. chunked INIT/APPEND/FINALIZE), the >5MB threshold, the need to poll STATUS, the 'exactly one of media_url or media' constraint, and the failure behavior ('STOP, do not substitute'). This is rich behavioral disclosure consistent with the false readOnly hint.

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 compact and information-dense, with the purpose front-loaded and every sentence contributing a distinct guideline. It covers use context, protocol branching, exclusion, parameter constraint, and failure handling without wordiness.

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?

The description is detailed about the upload flow, but with no output schema it omits what the tool returns—most importantly a media_id needed by sibling post/DM tools—and doesn't explain how the uploaded media should be consumed by downstream tools. This is a meaningful gap for an agent trying to chain calls 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 only 33%, so the description must compensate. It clarifies the core mutual exclusivity of media and media_url, and connects file-size/type behavior to the media parameter. It does not explain every nested field like data or encoding, but the schema already requires data and defaults encoding, so the added semantics are meaningful.

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 states a specific action ('Upload an image or video') with a clear resource scope ('for an organic post... or a DM') and names the exact media types involved. This clearly distinguishes the utility from sibling post/DM actions and leaves no ambiguity about what the tool does.

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?

It gives strong context for when to use this tool: uploading media for organic posts or DMs, with an explicit exclusion for ads ('Never amplify_video'). It does not explicitly name sibling alternatives like x_organic_create_post or x_organic_send_dm, but the purpose and media workflow are clear enough to guide selection.

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