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

The supplied annotations already cover safety traits (readOnly, idempotent, non-destructive, open world), so the description's real contribution is billing: ¥0.1 per call, charged only on success, with automatic refunds on failure or empty results. That is genuinely useful cost context, but the description says nothing about how many items come back or how to page through a large channel — a significant omission for a list tool.

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 tightly packed sentences with no filler: purpose and return shape first, then use cases, then billing. Every sentence carries distinct information and the most important framing is front-loaded.

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?

For a two-parameter read-only list tool with complete schema coverage and no output schema, this covers most of what an agent needs. The remaining gap is the boundary of the result set — item counts, whether pagination exists, and what a channel with no posts looks like despite the empty-result refund mention — which leaves the agent unable to plan multi-call collection.

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 both parameters, including the auth token fallback, are already documented in the schema itself. The description adds no meaning about the channel_id format (handle vs. channel ID) or how to obtain one, so it does not exceed the baseline that full schema coverage earns.

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 opens with a specific verb+resource phrase ('获取YouTube频道视频列表') and adds what the response contains: the account's published content in reverse-chronological order with per-item ID and basic engagement data. That is enough to separate it from yt_post_detail or yt_post_comments, though it never explicitly contrasts against the closest sibling, yt_user_info.

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?

It gives concrete when-to-use triggers: monitoring an account's posting frequency, studying content strategy, or bulk-collecting content IDs for an account. There is no when-not guidance and no named alternative for cases like keyword discovery, which yt_keyword_search covers.

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