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

Annotations already cover the safety profile (readOnly, non-destructive), and the description adds substantial operational context beyond them: the cap of 3 windows per platform, the minimum-2-posts threshold and its consequence, timezone resolution rules ('the zone you pass, or the zone the user schedules in'), and the YouTube exclusion. That is exactly the kind of behavior an agent needs to interpret empty or partial results.

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?

Four sentences, each carrying distinct information: purpose, return shape, minimum-data caveat, timezone handling, exclusions, and downstream use. The purpose and return contract are front-loaded with no filler.

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?

There is no output schema, so the description must carry the return contract, and it does: up to 3 windows per platform, window format, post counts, average engagement and views. Combined with full parameter documentation and annotations, an agent has everything needed to call it and interpret the result.

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%, so all four parameters are already documented, including the timezone fallback and the profileId/list_profiles pointer. The description reinforces the timezone default and the 'omit for every platform' behavior but adds no new syntax or format details beyond the schema. Baseline 3 applies.

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: finds the days/times the user's own posts got the most engagement, per platform, from recent history. This is clearly distinct from siblings like get_analytics or get_top_posts, which report metrics on posts rather than recommend posting windows.

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 routes the agent downstream: 'Use it to pick a scheduledFor for publish_scheduled or update_scheduled_post.' It also handles the failure case ('accounts with few posts get few or no windows; say so rather than guessing'). It doesn't explicitly state when to prefer get_analytics or get_top_posts instead, so it stops short of a full when/when-not/alternatives treatment.

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