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

Annotations already declare readOnly, idempotent and openWorld, so safety is covered; the description adds genuinely new context by disclosing the paged return behavior and the cost model ('1 credit per page'), which the agent would otherwise not know. It still doesn't say what each returned video entry contains.

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, output shape stated first and the cost/rate constraint second; every word carries information and nothing is padded.

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 read-only listing tool with annotation coverage and a fully described schema, the description covers purpose, paging and billing. The only gap is return-shape detail (what fields accompany each video), which matters somewhat because no output schema exists.

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%, so both parameters are documented in structured data; the description only reinforces paging semantics that the cursor field already implies. Baseline 3 applies since the schema carries the parameter burden.

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 ('Returns a YouTube playlist's title and videos') with an explicit scope modifier (one page at a time), which clearly separates it from get_channel_videos and search_youtube. It never names those siblings, so it stops short of full differentiation.

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 pick this over get_channel_videos or search_youtube, and no mention of required inputs or prerequisites beyond what the schema already requires. The only implicit hint is the pagination phrase, which the cursor parameter already conveys.

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