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

Annotations already cover read-only and idempotent behavior. The description adds behavioral context by listing the data the tool returns (body schema, reference body, seed envelope, media slots, prefills, override rules), which helps the agent predict what the response will contain. No contradiction with annotations was found.

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?

The description is a single information-dense sentence that front-loads the purpose and then lists contents in a structured series, followed by an actionable instruction. It is slightly long but each clause adds distinct value, so it earns a high mark.

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?

Given an output schema exists, the description does not need to explain return values. It fully covers what the tool provides, parameter context implicitly, and the critical timing relative to render_asset. The combination of annotations, schema coverage, and description is sufficient for correct invocation.

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?

The input schema already fully documents the single output_type parameter with a description and example values, so the description does not need to add param details. The description only implies that the output is for one film, which adds little beyond the schema; the schema carries the semantic weight.

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?

The description uses a clear verb 'describe' and identifies a specific resource ('one film') while enumerating exactly what the contract contains (body JSON Schema, media slots, brand prefills, override rules). It also distinguishes itself from render_asset by stating it is a prerequisite, which helps separate it from sibling tools.

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?

The description explicitly states when to call the tool: 'Call it before writing a render_asset body.' This is clear context but does not mention when not to use it or name alternative tools, so it falls short of the full 5-level guidance.

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