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

Annotations already declare readOnlyHint/idempotent/destructiveHint=false, and the description reinforces with 'Nothing is changed' while adding genuinely new behavior: the credit-cost model, including that free sources show expected_credit_cost 0 on apply_hero_pattern and made-for-you clips cost made_for_you_clip.credits. It stops short of describing the shape of the returned options or whether cost varies by site.

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 tight sentences with no filler, and the resource/scope is front-loaded ahead of the pricing note. The first sentence is a verbless fragment, which slightly hurts readability but not length economy.

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?

With no output schema, the description must convey what comes back, and it does: patterns, footage provenance, made-for-you availability, and price. The main remaining gap is how the price relates to the user's credit balance or whether the plan is per-site persistent, but for a read-only 2-param planning tool this is largely sufficient.

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% for both site_id and user_goal, so the schema already carries the parameter documentation. The description adds nothing about site_id scoping or how user_goal influences the returned pattern suggestions, so the baseline 3 applies.

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?

It names the specific resource (cinematic hero patterns) and enumerates what the result covers: footage sources, made-for-you clip availability, and cost. It implicitly distinguishes itself from apply_hero_pattern by referencing that tool for pricing. The one weakness is that no explicit verb states the operation (list/plan/retrieve), so the agent infers 'read the options' from the sentence fragment.

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?

'Nothing is changed' plus the pointer to apply_hero_pattern implies this is the inspect-before-apply step, which is useful routing context. However, it never explicitly says 'call this first, then call apply_hero_pattern' or states any exclusion, so the agent must infer the workflow from adjacency.

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