open_share

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

No annotations are provided, so the description carries the full behavioral burden. It discloses the essential side effect (the share is downloaded) and describes the return shape (caption, photos, per-video file/length/preview composed of 6 frames). It omits permission requirements, whether the download persists, and whether the operation mutates message state, which keeps it short of a 5.

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?

Purpose and primary usage guidance are front-loaded, and the paragraph structure separates the action, the return value, the follow-up inspection recipe, and the alternative tool. The embedded ffmpeg commands are verbose but operationally useful rather than filler, so only a minor deduction for density.

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?

An output schema exists, yet the description still helpfully characterizes the return (caption, photos, per-video file and preview), so nothing essential is missing for invocation. Residual gaps are unstated permissions/authentication and whether re-opening re-downloads, but the definition is otherwise complete for this complexity level.

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 0%, so the description must compensate, and it does: message_id is defined as 'Message id of the share, from the channel event' and 'to' as 'Chat alias. Omit for the sole subscribed target.' Both parameters gain meaning beyond the bare schema types.

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 verb and resource ('Open a shared reel, post or story: download it and see what's in it') and clarifies the downstream effect (downloading the media). It differentiates from siblings by naming transcribe_share as the tool for audio content, 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?

Explicit guidance is given on how to use the output ('Read the preview first'), how to inspect media further ('pull frames yourself' with exact ffmpeg commands), and when to switch tools ('For what is said, call transcribe_share'). This covers when-to-use and the alternative, which is exactly the bar for a 5.

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