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

Annotations already declare readOnlyHint=false, openWorldHint=true and non-idempotent, so the safety profile is covered. The description adds cost/consumption context the annotations cannot convey — 'Counts as 1 AI text generation' — which is directly relevant to an agent deciding whether to call it. It stops short of describing what downstream state changes (if any) occur.

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?

Short and front-loaded, with platform targeting and cost placed after the core purpose. The first line 'Generate a video caption' largely restates the tool name and the following sentence, a minor 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 3-parameter, no-output-schema generation tool, the description covers purpose, platform optimization, and credit cost — enough to call it correctly. It could improve by naming the sibling it replaces and by clarifying whether it only returns a draft or also persists anything.

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 67%, and the two documented parameters (contentGroupId brand grounding, existingContent as an improvement target) already carry their meaning in the schema. The description adds no parameter-level detail and leaves videoTitle entirely unexplained in both places, so it does not compensate for the coverage gap.

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?

Specific verb+resource ('Generate a video caption') with concrete scope: short-form vertical video platforms (TikTok/Reels/Shorts) and output style (hooks, CTAs). It distinguishes itself somewhat from generateCaption by the 'video' qualifier, but never explicitly contrasts with the sibling generateCaption or generateCarouselCaption, so an agent must infer the boundary.

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?

Usage is implied rather than stated: 'for a video post' signals the context in which to pick this over generic captioning. There is no explicit when-not guidance and no named alternative (generateCaption, generateCarouselCaption) despite three near-identical siblings.

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