Get the watchlist

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

Annotations already declare readOnlyHint=true, and the description's closing 'Read only' restates that rather than adding to it. It does add genuinely useful non-obvious context: the numbers are Runsheet's stored copy of public YouTube data, refreshed in the background and held for at most 30 days, so results may be stale rather than live. That is solid disclosure, but it says nothing about empty watchlists, error behavior, or cost.

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?

Front-loaded with what the tool returns, and the definition of 'breakout videos' earns its space because no output schema exists to explain it. Three dense sentences with little waste, though the parenthetical definition is slightly long.

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 carries the full burden of describing returns, and it does so well: per-channel metrics, the creator's own baseline numbers, and the watch_id/video_id handles. It still omits edge cases such as what an empty watchlist returns or any access prerequisites.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a parameterless tool applies. The description instead documents the shape of the returned IDs, which is a reasonable substitute.

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 and resource ('the other YouTube channels this channel watches') and enumerates the exact metrics returned (uploads/week, Shorts share, breakout videos). It is clearly distinguishable from siblings like runsheet_get_channel because it describes the comparison against the creator's own numbers and names the downstream consumer of the IDs.

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?

Clearly establishes the context of use: it returns watch_id and video_id values that runsheet_break_down_breakout takes, effectively routing the agent to the next tool. However, it gives no explicit exclusions or when-not-to-use guidance relative to siblings such as runsheet_get_channel.

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