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

Annotations cover the safety profile (mutation, non-idempotent, closed-world), and the description adds real behavioral context beyond them: work is asynchronous ("audio and assembly run in the background"), the immediate return is {id, status: building}, and scenario errors surface synchronously by scene number. That async/error contract is exactly what an agent needs for a long-running build.

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-loaded with the action ("Build a lecture lesson"), then the immediate return and the background/error behavior. Slightly dense with parentheticals and a docs pointer interrupting the first clause, but no wasted sentences.

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?

With no output schema, the description carries the return contract and does it well (id + status: building, async completion, error timing). For a one-parameter create tool the only remaining gap is the concrete scenario format, which is offloaded to docs by design.

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?

There is a single required parameter (scenario) with 0% schema description coverage, so the description must compensate. It characterizes the value as a "v2 scenario" with "format, rules and an example" and points to docs("lessons"), which is helpful, but it does not inline the scenario shape, so the gap is only partially closed.

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 and resource ("Build a lecture lesson from a v2 scenario"), so the agent knows it creates a lesson audio/scene artifact. It gives no differentiation from siblings like lesson_audio, lesson_open, or lesson_get, so the agent must infer the boundary itself.

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 by the name and verb, and it routes the agent to docs("lessons") for the scenario format, which is useful setup context. However, it never states when to prefer this over lesson_audio or lesson_get, nor any prerequisites, so guidance is only implied.

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