List the channel’s playlists (and what is in one)

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

Annotations already provide readOnlyHint=true and destructiveHint=false, but the description adds substantial extra context: it states 'Read-only, 0 credits' (credit cost beyond annotations), explains the output fields per playlist, and details the critical distinction between videoId and itemId for playlist entries, including the reason (a video can appear more than once). This goes well beyond the annotation hints and informs correct downstream usage.

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 yet efficient. The first sentence states the core purpose, the second covers the optional parameter usage, and the third (IMPORTANT) conveys a critical nuance. Every sentence earns its place, and the critical information is front-loaded. No filler or redundancy.

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 must explain the return shape, and it does: playlists carry id, title, description, privacy, video count; entries are returned in order and carry both videoId and itemId. It also notes pagination indirectly via the pageToken parameter in the schema. Credit cost and prerequisite are stated. Missing minor details like exact pagination behavior or other optional fields, but overall it is complete enough for an agent to call correctly.

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 coverage is 100% and each parameter already has a clear description. The tool description adds marginal semantics for playlistId by reiterating its effect ('get that ONE playlist plus its entries'), but the limit and pageToken are not elaborated beyond the schema. Since the schema does the heavy lifting, a baseline of 3 is appropriate; the description adds little that isn't already knowable from the schema.

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 states a specific verb+resource: 'List the playlists on the connected YouTube channel' and enumerates exactly what is returned (id, title, description, privacy, video count). It also distinguishes the optional playlistId mode as 'get that ONE playlist plus its entries'. This clearly separates it from sibling tools like manage_youtube_playlist_items or list_youtube_videos.

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 description gives explicit usage guidance: 'Pass a playlistId to get that ONE playlist plus its entries' versus omitting it to list the channel's playlists. It also mentions the prerequisite ('Needs a connected YouTube channel') and references the related management tool (manage_youtube_playlist_items) to clarify the id semantics. It does not explicitly state exclusions or alternatives, but the conditions for use are clear.

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