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

The description discloses a rich set of behaviors the annotations cannot express: it costs nothing ('Free'), the link expires in ~a day, files are large (130 MB example), builds may complete async requiring a second call with exportId, only one build per account runs at a time, and a busy service returns retryAfterSeconds. All of this is consistent with readOnlyHint=false and idempotentHint=true, with no contradictions.

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?

Every sentence carries a distinct fact — cost, formats, link TTL, file size, async pattern, concurrency, busy behavior, prerequisite — with zero filler. Key decision information (free, formats) is front-loaded in the first two 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?

Despite having no output schema, the description documents the response branches an agent needs: a download URL, an exportId for retry, alreadyExporting with projectId, and retryAfterSeconds on refusal. Combined with full parameter coverage and the assemble-first prerequisite, there is no critical gap for correct invocation.

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?

With 75% schema coverage the baseline is 3, and the description adds real meaning: it explains what each format actually produces ('epub' is fixed-layout Kindle ready, 'cbz' for comic readers, 'bundle' contains all three plus page PNGs) and clarifies the exportId workflow. The only parameter it doesn't deepen is projectId, which is self-evident.

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?

Uses a specific verb ('builds'/'export') with a concrete resource ('the assembled book'), enumerates all output formats with real meaning, and distinguishes itself from the aetherwave_comic_assemble workflow step via the closing 'Assemble first' hint. An agent can tell this produces a downloadable file vs. the sibling creation/assembly tools without opening the schema.

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?

Provides clear when-to-call context: 'Assemble first' states the prerequisite, the exportId retry path explains when to re-invoke, and the concurrency note tells the agent it may receive alreadyExporting instead of a new build. It stops short of naming sibling alternatives explicitly (e.g., using aetherwave_comic_status to monitor), so it doesn't quite earn a 5.

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