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

Annotations already pin it as readOnly, idempotent, non-destructive and closed-world, so the safety profile needs no restating. The description adds real value by disclosing the conditional shape of the response — results always, best_times only when timezone is passed — and by framing the best_times data as local-hour aggregates rather than raw events.

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?

It is a single dense sentence, front-loaded with the primary payload and keeping the timezone-dependent branch subordinate. The parenthetical output-section names (results, best_times) aid scanning, though the sentence is long enough that an agent may need a second pass to parse the conditional.

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 an output schema present, the description does not need to enumerate return fields, and it doesn't overreach — it names the two response sections and the condition that produces one of them. Combined with rich annotations and a one-parameter schema, this is nearly everything an agent needs to invoke it correctly; only an explicit 'timezone is optional' statement is missing.

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 0%, so the description must carry the single parameter, and it does: timezone is an IANA zone with a concrete example (Europe/Paris) and a stated effect on the response (local-hour best_times). It never explicitly labels the parameter optional, though the conditional phrasing implies the results-only default.

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?

Names the resource (the reader's published posts) and the exact metrics returned (views, likes, comments, shares per account) plus the secondary output (best_times). It also names the sibling it feeds into (schedule_post), so an agent can separate it from list_posts or get_benchmark without reading 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?

Gives a clear use case: it is the tool to call when deciding when schedule_post should publish, and it states that best_times only appears when timezone is supplied. It stops short of naming an alternative for cases where the agent wants post listings rather than performance, leaving that inference to the sibling name.

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