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

Annotations already declare readOnlyHint and destructiveHint=false, yet the description adds substantial behavior the annotations cannot: metricsAvailable indicates whether post counters are reportable at all, statsAt/metricsAt indicate read freshness, and on platform failure the tool degrades to the latest daily snapshot with statsError explaining why. It also discloses per-network semantic differences (views only on YouTube; 'videos' means video count on YouTube but post count elsewhere).

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?

The description is dense and front-loads the returned data before explaining field semantics and the failure fallback. Every sentence carries information, though the run-on enumeration of field meanings in one block makes it slightly harder to scan than a short structured list would be.

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, the description properly takes on explaining return values, field meaning, and degraded-mode behavior, which it does thoroughly. The remaining gap is volume/shape of the 'posts in the period' collection — nothing says whether it is truncated, paginated, or bounded by days.

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% for both parameters, so channelId and days are already documented in the schema. The description only indirectly touches parameters via 'posts in the period' and never clarifies the day-range default or cap. Baseline 3 is appropriate when the schema carries the parameter burden.

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 description names a specific resource and enumerates its contents: channel totals, posts in the period, their counters, and stored daily history. That is far more informative than the title alone. It stops short of distinguishing itself from plausible siblings like get_analytics_overview or get_post_metrics, so an agent must infer the boundary itself.

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?

There is no explicit statement of when to call this versus get_analytics_overview, get_post_metrics, or list_posts. The only contextual cue is the implicit note that channel totals are read live, which hints at freshness rather than tool selection. An agent gets no when-not or alternative routing.

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