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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), and the description adds genuine context beyond them: the preview URL is 'private, never-indexed,' only the owner can run it, and it reads World Bank/FRED/Eurostat/connector data through the sandbox bridge. It also discloses that public_url is null while private and that next_step names the next call. No contradiction with annotations; only failure states and URL lifespan are left out.

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?

Three sentences, front-loaded with the core purpose, then return-field semantics, then usage guidance — every sentence earns its place. The middle sentence carries a lengthy nested parenthetical about data sources, which is informative but slightly dense.

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 present, the description compensates well by enumerating the return fields and their meanings, while the single required parameter keeps complexity low. It explains reuse (shareable link after publish) and next-step routing, though it omits error cases and any expiry/refresh behavior of the preview URL.

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% — app_id is already documented as 'The app id' — so the baseline is 3. The description adds only a mild ownership constraint ('an app you own'), which is useful but does not meaningfully extend the parameter's semantics beyond what the schema provides.

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 opening line states a concrete resource — the preview URL for an app you own — with a clear verb ('OPEN') and scope ('plus where it stands'). The description further distinguishes the tool by enumerating its unique outputs (preview_url, public_url, visibility, indexed, next_step), which separates it from siblings like list_apps and get_app_context. It never names a sibling explicitly, so it stops short of a 5.

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 explicitly anchors the tool in a workflow: 'Use it to hand a user something to click after create_app, and to check what is still missing before publish_app.' This tells an agent exactly when in the app lifecycle to call it. However, it offers no when-not-to-use guidance and names no alternative tools, so it misses the bar for a 5.

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