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

With no annotations, the description carries the full burden, and it does disclose two real behavioral facts: the call costs 1 credit and requires an Authorization Bearer header. However, it says nothing about whether the call is read-only, what 'stats' actually contains, or any rate/limit behavior.

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?

Extremely tight, front-loaded with the purpose before the metadata clauses. Minor blemish: the stray double period after 'id..' suggests mechanical generation rather than clean prose.

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 single-parameter read with no output schema, the description covers purpose, cost, and auth but never says what fields the 'public stats' return or what happens on an invalid/non-existent id, leaving an agent guessing about the response shape.

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 the single 'id' parameter is fully documented in the schema with an example, so the description adds nothing beyond 'by id'. Baseline 3 applies when the schema does the heavy lifting.

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: 'Fetch public stats for a video or Short by id.' It distinguishes itself reasonably from the list-style siblings (youtube_videos, youtube_shorts) by being single-item, though the 'video or Short' overlap with those siblings is not explicitly resolved.

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?

There is no statement of when to use this versus youtube_videos, youtube_shorts, or youtube_resolve – all of which deal with YouTube video resources. The only implicit cue is 'by id', leaving the agent to infer the selection condition.

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