YouTube: Auth Status

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds genuinely new behavior: the quota cost model ('1 quota unit the first time it resolves the channel, then nothing') and the fact that an unconfigured server returns actionable setup steps. The channel-ownership caveat (the token picks the channel, so this is where uploads land) is also useful operational context.

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 dense sentences, each carrying distinct information: what is reported, the unconfigured behavior, and the diagnostic trigger plus cost. No filler, though the first sentence is a long comma-separated list that is harder to scan than it needs to be.

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 return content, and it does so by enumerating every reported field plus the conditional setup-steps response. For a zero-param, read-only diagnostic tool this leaves nothing material for an agent to guess.

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?

Zero parameters, so there is nothing for the schema to describe beyond an empty object and nothing the description needs to compensate for. Baseline 4 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 enumerates exactly what the tool reports: configuration/sign-in state, the acting channel, granted scopes, whether write tools are registered, and the quota model. That is specific enough to separate it from youtube_auth_login and youtube_auth_logout, though the opening is a noun-phrase list rather than an explicit verb+resource statement.

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 a concrete trigger — 'Call this first when a tool you expected is missing' — and notes the unconfigured path returns setup steps, which steers an agent toward it as a diagnostic. It stops short of explicitly naming the sibling login/logout tools as alternatives for the unconfigured case.

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