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

Annotations only cover readOnlyHint and openWorldHint. The description adds substantial behavioral context: the 90-day lookback window, the fact that ranking methodology differs by platform (engagement-weighted vs post-frequency for LinkedIn/Threads/TikTok with 'engagement collection deferred'), timezone defaults, and the paid-plan gate. This exceeds what structured fields provide.

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 covering purpose, per-platform behavior, timezone, and plan requirement. Front-loaded with the core purpose, no filler, every sentence earns its place.

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 needn't detail return values. It covers purpose, platform-specific behavior, timezone handling, and plan gating. The one gap is explaining the topN parameter, which is relevant since the description mentions ranked slots but not the count control.

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 compensate. It explains that platform determines ranking methodology and that timezone is IANA-format with a UTC default. It does not describe the topN parameter, which is a gap, but the two most semantically rich parameters are covered.

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+resource ('Recommend the best (dayOfWeek, hour) slots') with precise scope: 'for the user's next post on a given platform, ranked by engagement-per-post over the past 90 days.' This is clearly distinguishable from siblings like get_channel_analytics or get_post_metrics.

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 makes clear when to use it (scheduling the next post, per platform) and states a hard prerequisite ('Paid plan required'). However, it doesn't name alternative tools or explicitly say when not to use it versus get_channel_analytics.

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