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

With no annotations, the description carries the full burden, and it does disclose two meaningful behaviors: the operation is 'free of charge' (no credit consumption) and a shot lacking a start frame always receives the added still as its start frame. It omits mutation/reversibility framing, concurrency behavior, and any error conditions, so the disclosure is partial for a write operation.

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 sentences, front-loaded with the core action and its cost implication, followed by the option semantics. No filler or repetition.

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 five-parameter write tool with no annotations, no output schema, and zero schema-level descriptions, the description covers the most interesting flag but leaves the required version parameter and the return behavior unaddressed. An agent could call it, but could plausibly mishandle expectedVersion.

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 0% across five parameters, yet the description explains only asStartFrame in depth, including its fallback semantics when no start frame exists. The required expectedVersion parameter (clearly an optimistic-concurrency token) is never explained, and shotId/projectId/assetId are left to name inference.

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 and resource ('Add an existing image asset ... to a shot's stills') and names concrete asset sources (asset.capture_frame output, an upload), which helps distinguish it from asset-producing siblings. It does not, however, disambiguate against the close-in-name siblings shot.select_keyframe / shot.generate_keyframe, leaving an agent to infer how 'stills' relate to 'keyframes'.

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 phrase 'Add an existing image asset (e.g. a frame from asset.capture_frame, or an upload)' implicitly tells the agent it must first produce an asset elsewhere, which is useful routing context. There is no explicit when-not-to-use guidance or statement of the relationship to shot.select_keyframe, so usage is only implied.

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