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

Annotations already establish readOnly, non-destructive, closed-world behavior, and the description adds material context beyond them: the operation costs no credits and returns a set of candidates from which one is chosen. It doesn't describe count or format of returned hooks, but the output schema covers that.

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 dense sentences with the output, the selection constraint, the downstream tool, and the cost all front-loaded; no filler whatsoever.

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 one-parameter suggestion tool with a full output schema, everything an agent needs is present: what it returns, how to use the result, and that it is free. Nothing material is missing.

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 baseline is 3, but the description adds meaning the schema cannot: the context parameter is optional because the app profile may already be on file. That clarifies the required=0 situation rather than just restating it.

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 (suggest) and resource (short hook lines) with a precise scope: the first frame of a UGC video. It is clearly distinguishable from the other suggest_* siblings (suggest_influencers, suggest_reactions) without opening any schema.

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?

Gives explicit downstream routing: pick one line and pass it to make_video, plus the 150-character constraint. It doesn't name an alternative or a when-not-to-use condition, but for a suggestion helper the context is unambiguous.

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