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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the write/non-idempotent profile is covered structurally. The description adds genuinely new context: the 50-unit YouTube Data API quota cost and that the new playlist is returned. It stops short of saying what happens on quota exhaustion or duplicate titles.

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?

Two short sentences with zero filler: the action is front-loaded, followed by the return value and the quota cost. Every sentence carries information an agent needs.

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 create tool with no output schema, the description covers the return value ('returns the new playlist'), the auth prerequisite (connected channel), and the quota cost. Only edge-case behavior on failure is unaddressed, which is a minor gap.

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%, with the title length limit, profile_id meaning, and privacy_status default all documented in the schema. The description adds no parameter-level detail beyond that, so the baseline of 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 states a specific verb and resource: 'Create a playlist on a connected YouTube channel.' Combined with the tool name, an agent can distinguish it from youtube_playlist_delete, youtube_playlist_update, and youtube_playlists_list. It doesn't explicitly name those siblings, but the verb contrast is unambiguous.

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?

Usage is implied by 'on a connected YouTube channel', which signals that a connected YouTube profile is required, but there is no explicit statement of when to choose this over youtube_playlist_update or youtube_playlists_list, and no mention of failure conditions such as an unconnected channel or exhausted quota.

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