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

With no annotations, the description carries the full burden and does so unusually well: it discloses the payment model ($0.06 deposit per call in Nano/XNO, settled at actual cost +20% with change returned), that no account is needed, observed latency (~1m 48s), last-run cost, and that outputs are images saved to disk with file paths in the result. It also flags a two-phase payment/results flow via _payment_id and the companion rig.mjs baking 32 frames.

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 content is dense but poorly front-loaded: pricing, links, an example URL, and a truncated node-graph string are interleaved with the core flow, so the key 'what it does / what it returns' information is not cleanly ordered. Sentences carry real information but the structure impedes fast scanning.

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 multi-call, paid, no-output-schema tool, the description covers cost, payment flow, auth requirement, return type and on-disk output location, plus a working example and an external skill link. It is close to complete; the main omission is any mention of failure/refund or retry behavior if the image calls fail.

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 Character, Character_designer and _payment_id are already documented in the schema with defaults and usage notes, making the baseline 3 appropriate. The description adds only the high-level notion of 'one text call' and does not elaborate parameter syntax or meaningful defaults beyond what the schema says.

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 concrete pipeline (description → canonical character → cutout parts → local rig/animation baking) with explicit call counts (one text call + two image calls), so the resource and operation are identifiable and distinct from sibling image/video tools. However, the purpose is embedded in a garbled diagram fragment ('id… text:Character -> llm:Character designer -> image:Canonical character') that muddies what the tool itself returns versus what the companion skill 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 offers a use-case vignette (a playable fighting game, with 'a coding agent adds combat, gravity and game rules') but never states when to choose this tool over siblings like storyboard-relay or talking-avatar, nor any when-not condition. The agent must infer applicability from the example alone.

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