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

The annotations already cover the safe-mutation profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true, openWorldHint=false), and the description adds genuinely new information the annotations lack: no paid generation and no model call are triggered. However, it says nothing about what the resulting 'shell' contains, whether creation consumes quota or the title must be unique, or what state is required before generation can follow.

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 eleven-word sentence with the verb and resource front-loaded and no filler. It loses a point only because 'Film shell' is undefined jargon that an unfamiliar agent must guess at.

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?

Because an output schema exists, the description need not explain return values, which offsets some of its brevity. But for a three-required-parameter creation tool sitting among several other create_*_project siblings, one sentence leaves gaps: what a shell is, whether the created project needs activation, and which sibling to pick for a series or ads project.

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 67%: title and request_key are documented in the schema, while aspect_ratio (an enum of three self-evident values) is not. The description adds nothing about any parameter, but with two of three documented and the third being a trivial enum, the schema does most of the work and 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?

Specific verb ('Create') plus resource ('a Film shell'), and it immediately qualifies scope as 'without paid generation or a model call', which distinguishes it from generation siblings like generate_scene_media or assemble_film_edit. It does not name a specific sibling it could be confused with (create_series_project, create_genads_project, native.create_project), so it stops just short of full 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?

The clause 'without paid generation or a model call' implies the use case (scaffold an empty project container cheaply before spending), but the agent must infer that. There is no explicit 'use this instead of X' routing, no prerequisites, and no statement of what the caller should do after creation (e.g. add scenes, then generate).

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