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

The description states this is a paid operation that bills when the video arrives, while annotations declare readOnlyHint=true. This is a direct contradiction—the tool creates a resource and incurs cost, not a read-only operation. The description itself is transparent about billing and async behavior, but the contradiction with annotations is severe.

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 with no fluff. The purpose is front-loaded, followed by the async flow and billing caveat. Every sentence earns its place.

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 covers the essential usage: returns a video id, poll with video_status, and billing details. All parameters are in the schema. However, the annotation contradiction undermines trust and could mislead an agent about side effects, so completeness is slightly reduced from an ideal 5.

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%, with all six parameters documented in the schema. The description only reiterates the duration (6 or 10 seconds) and does not add meaningful semantics beyond the schema. Baseline 3 applies because the schema carries the parameter detail.

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 tool's purpose: generating a short video clip (6 or 10 seconds) with Grok Imagine. It distinguishes itself from siblings by naming video_status for polling and implying generate_image for images, so an agent can easily differentiate.

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 explicitly instructs to poll with video_status until done, providing a clear usage flow. It doesn't explicitly state when not to use it (e.g., for images) but the purpose is specific enough that alternatives are obvious.

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