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

With no annotations, the description carries the full burden and does well: it discloses the account requirement, that invoking it may trigger a sign-in prompt on the user's behalf, and the alternate continue_url flow. It does not mention credit consumption, rate limits, or whether previews expire — minor gaps for a gated data tool.

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 sentences, front-loaded with the payload contents before the prerequisites. The output enumeration is long but each item is distinct and informative; no filler prose.

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?

No output schema exists, so the description must describe return values — and it does, listing the breakdown components. Auth/sign-in behavior is covered. Missing only edge details such as what happens if preview_id is stale or the preview has expired.

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?

Single parameter with 100% schema description coverage; the schema already says preview_id comes from preview_profile, and the description only repeats that lineage. Baseline 3 applies since the schema does the heavy lifting.

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 (preview insights) and resource scope ('for a previewed profile'), and enumerates exactly what the breakdown contains: best day, hour, format and length, top/bottom 5 posts with reasons, engagement trend by format. The 'previewed profile (from preview_profile)' framing separates it from the sibling get_posting_insights, which operates on claimed profiles.

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?

Explicitly states the prerequisite ('Requires a free Flux account') and gives the fallback path ('otherwise use continue_url from preview_profile') when the client cannot prompt for sign-in. It does not explicitly compare against get_posting_insights, but the dependency on preview_id makes the intended call sequence clear.

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