Analyze channel & recommend

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, non-destructive), yet the description adds real behavioral detail beyond them: it discloses an internal video sync step, a current-vs-previous period comparison, a same-format baseline against the channel's own history, and that output is exactly one recommendation. The undisclosed cost here is that this is a multi-step, potentially slow operation, which the description does not warn about; 'syncs videos' also sits in mild tension with readOnlyHint, though a cache refresh is plausibly non-mutating and idempotent.

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 dense sentence, but it is front-loaded with the tool's identity and each clause (sync, period comparison, per-video diagnosis, rising/declining detection, single recommendation) adds distinct information. It borders on being a run-on list, though no clause is pure 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?

With an output schema present, the description needn't explain return structure, and it still usefully signals that output is one prioritized recommendation rather than a report dump. What is missing for a genuinely heavy orchestration tool is a note on runtime/cost or side effects of the sync step, which would help an agent decide whether to call it or a cheaper sibling first.

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% and both parameters are documented in the schema, including the default channel fallback and the 14-180 day bound. The description only echoes the comparison-window semantics for `days` ('this and the previous period') and says nothing about channel_id behavior, so it adds little beyond structured fields – 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?

States a specific verb chain and resource: 'End-to-end health check: syncs videos, pulls analytics... diagnoses each video's bottleneck... returns ONE prioritized recommendation.' This is clearly distinguishable from siblings like youtube_get_channel_analytics (raw metrics) and youtube_get_channel_overview (summary), since the description emphasizes diagnosis plus a single actionable recommendation.

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 phrase 'End-to-end health check' plus the bottleneck taxonomy gives strong implied context for when to reach for this tool over the narrower analytics siblings. However, it never states when NOT to use it (e.g., for a quick metric pull prefer youtube_get_channel_analytics) nor that it is a heavier multi-step operation, leaving the agent to infer the trade-off.

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