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

Goes well beyond the annotations by disclosing the credit spend, the free stand-in that plays until a commissioned clip arrives, the price-mismatch refusal with no charge, idempotency-key reuse to avoid double billing, version-history recording, and that publishing is required for visitors to see the result. These are exactly the side effects an agent needs before a mutating, credit-consuming call.

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?

A single dense paragraph that front-loads the pattern taxonomy before the cost/precondition rules, with no filler sentences. The heavy use of capitalization and em-dashes makes it slightly harder to scan than a short bulleted structure would be.

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 an 18-parameter mutation with no output schema, the description covers the cost model, idempotency, the plan-then-apply workflow, and the publish step — enough to call it safely. It stops short of describing what the tool returns or how to verify success beyond 'recorded in version history'.

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 89%, so the baseline is 3; the description adds real meaning on top by linking expected_credit_cost to plan_hero_pattern, framing idempotency_key as retry-safety, and clarifying which video_source values are free versus paid. Minor gap: chapters vs chapter_title/eyebrow/subtitle mutual exclusivity is only implied by the schema field notes, not stated here.

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?

Opens with a specific verb+object ('Replace a design's hero section with a cinematic pattern') and then defines each of the four enum values in behavioral terms (scroll-driven, cursor-driven, pan/zoom, particles). This makes the tool unambiguously distinct from the sibling plan_hero_pattern, which only plans.

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?

Explicitly states the prerequisite ('Call plan_hero_pattern first') and the cost/refusal contract (send expected_credit_cost, mismatch is refused with nothing charged). It explains which sources are free vs credit-spending, but never states when NOT to use this tool (e.g. theme-level changes belong to apply_theme or variation work to patch_variation_content).

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