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

With no annotations, the description carries the full burden; it does disclose two valuable behaviors: cost ('metered in credits unless the owner uses their own Anthropic key') and that exactly three variants are returned. It is silent on whether drafts are persisted, whether calls are idempotent, what happens to previously drafted prompts, and whether there are rate limits or latency expectations.

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 tight sentences with the core action front-loaded and the cost caveat parenthesized rather than buried. Nothing is redundant, though the cost clause could be ordered after the workflow pointer for tighter reading flow.

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 six-parameter tool with zero annotation and zero schema-description coverage and no output schema, the description is thin: it explains purpose, cost, and next step, but leaves every input undefined. An agent could select this tool correctly yet still not know how to fill guidance or the optional scene-context fields.

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% across six parameters, so the description must compensate, and it largely does not. It hints that the target is a 'scene's asset' (gesturing at assetType) but never explains what 'guidance' should contain, how currentText/sceneSummary/sceneTitle influence the drafts, or that guidance is required.

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 ('Draft three alternative generation prompts') plus the scope ('for a scene's asset'), which distinguishes it from generic prompt mutators. It does not explicitly differentiate from close siblings like shot.draft or music.compile_prompt, so the agent must infer the boundary from 'scene's asset'.

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?

The description implies the workflow by naming the follow-up action ('attach one to a scene with prompt.attach'), which is useful routing. However, there is no explicit when-to-use versus when-not guidance, and no mention of when a sibling drafting tool (shot.draft, music.compile_prompt, voice.compile) would be the better choice.

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