Channel analytics

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is fully covered by structured fields. The description adds one piece of real context beyond that — 'Private', signalling the data is scoped to the caller's own authenticated channel — plus a low-cost summary of what the payload contains. It says nothing about rate limits, quota cost, or empty-data behavior, so it is value-adding but not rich.

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?

A single front-loaded sentence fragment that wastes no words, with the distinguishing qualifier ('Private') placed first and the payload contents listed after. It is efficient, though the colon-list format is clipped enough that it reads as a label rather than an instruction.

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?

An output schema exists, so return-value explanation is not required, and annotations cover the safety profile; with only two well-documented parameters the definition is close to sufficient. The remaining gap is selection guidance against four sibling analytics/overview tools, which the description does not address at all.

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%: the 'days' parameter already documents the window and that it compares against a previous window of equal length, and 'channel_id' documents the UC... format and the omit-to-use-default behavior. The description adds no syntax, defaults, or edge cases on top of that, so the 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?

The description names the resource (channel analytics) and enumerates the concrete outputs: period-over-period totals, daily trend, traffic sources, countries, and subscriber split. That is specific enough for an agent to know what data it yields, but it never distinguishes this tool from likely-overlapping siblings such as youtube_get_channel_overview or youtube_analyze_channel_performance.

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 when-to-use guidance at all: no statement about when this beats youtube_get_channel_overview, youtube_get_video_analytics, or youtube_analyze_channel_performance, and no prerequisites such as needing a connected channel. The only hint is the word 'Private', which implies an authenticated/owned channel but does not route the agent between alternatives.

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