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

Annotations already declare non-read-only, idempotent, non-destructive, closed-world, and the description goes well beyond them: async background design taking 1–2 minutes, immediate return of a review link, retry-on-failure with the same set_id, no charge for failed runs, and the tablet set counting as a second generation requiring an API key.

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 and workflow position, then async behavior, then input guidance; nearly every sentence carries operational information. The app_description paragraph is slightly editorial but still earns its place by shaping output quality.

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 an 8-parameter, asynchronous generation tool with no output schema, the description supplies everything an agent needs: upstream/downstream siblings, async timing, retry semantics, cost implications, and how to supply inputs in either mode.

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 coverage is 100% so baseline is 3, but the description adds real semantic guidance the schema lacks: prefer set_id over inline screenshots, keep base64 under ~1 MB, and how to source app_description (README/store listing/product copy, specific beats generic).

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 — designing a finished App Store / Google Play screenshot set from uploaded screenshots — and places it as "Step 2 of 3" in a named workflow, which distinguishes it from prepare_screenshot_upload and get_screenshot_set without opening any 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?

Explicit sequencing: call prepare_screenshot_upload first, then this tool, then get_screenshot_set to wait for the result. It also gives a concrete fallback condition ("if you cannot run shell commands") for the inline base64 path and states set_id is preferred.

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