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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so 'Reads nothing and changes nothing' largely restates structured data. The real added value is the non-obvious two-step contract: the tool returns a brief the agent must then follow rather than producing the script, and 'the brief asks for the rest' signals the return will drive a follow-up prompt.

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 tight sentences with no waste; the most decision-relevant fact (this returns a brief, not a script) is front-loaded immediately after the entry-point cue.

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?

Output schema exists so return-format detail is unnecessary, and annotations cover the safety profile. For a zero-required-param, read-only brief tool the description supplies everything an agent needs: when to call it, what it returns, and how to proceed afterward.

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%, so the schema documents all four params including tone/character enumerations, setting the baseline at 3. The description adds genuine usage meaning by explaining the fill-what-you-have pattern and that the brief will elicit the remainder, which the schema alone does not convey.

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+resource ('Returns Alpy's YouTube scriptwriting brief') and crucially corrects the name's implication that this tool writes a script itself. The contract is unambiguous. It never names a sibling (create_video, make_full_video) explicitly, so it stops short of full sibling 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?

'Start here for any Alpy script' gives a clear entry-point condition, and the guidance to pass only the fields the creator already supplied tells the agent how to invoke it under partial information. There is no explicit when-not or named alternative for other outcomes.

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