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

Adds a lot beyond the annotations: upload must complete within expires_in_seconds, the video is only ever published on Instagram and never used in a page, and Saypage deletes an unpublished one at video_expires_at (an hour). It also spells out the exact transfer mechanics (PUT with upload_headers or multipart POST with upload_fields).

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?

Front-loads the primary instruction and the chat-app alternative in the first two lines, then the mechanical steps. Every sentence carries actionable information despite the slightly fragmented line breaks.

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?

Covers the full lifecycle (initiate, transfer, confirm, expiry/cleanup) for a mutation tool, and an output schema exists so return values need no explanation. Nothing an agent needs in order to call it is missing.

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%, so filename/content_type/size_bytes are already documented, and the description does not add meaning to them. Its upload_headers/upload_fields guidance concerns the upload handshake rather than the three declared parameters.

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?

States a specific verb+resource (upload a local video) and scopes it to a Reel or video story. It distinguishes itself from request_upload_link and start_image_upload by naming both, so an agent can route correctly without opening schemas.

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?

Explicitly splits the audience: assistants that can run shell commands use this tool, chat apps use request_upload_link. It also names the follow-up step (confirm_video_upload) and the time window, leaving nothing to inference.

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