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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=true, so safety and repeatability are covered. The description adds real value by disclosing that the call costs 0 credits and that the daily free-tier quota resets on a schedule, but says nothing about auth requirements or how the tier affects results.

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, front-loaded sentences: the first enumerates exactly what is returned, the second removes cost-hesitation with 'Free (costs 0 credits).' No filler, no repetition of the title.

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?

A simple zero-param reader with no output schema, so the description only needs to say what comes back and what it costs, which it does. It stops short of describing the shape of the returned balance/tier fields, though the enumeration of returned items largely covers that.

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?

There are zero parameters and the schema is a closed empty object, so the baseline for this dimension is 4. The description correctly implies no inputs are needed and adds no parameter claims that would need schema backing.

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: checks the YTAPI credit balance, account tier, and daily free-tier quota reset time. This is clearly distinguished from all siblings (get_channel, get_transcript, search_youtube), which are content-retrieval tools, whereas this one reports account-level state.

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?

Implies usage (check remaining credits/tier/reset time) but gives no explicit when-to-use or when-not-to-use guidance, and names no alternatives. For a zero-param, zero-cost utility tool the implied usage is fairly self-evident, so 3 is reasonable rather than a hard gap.

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