preview

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

With no annotations, the description carries the full burden. It discloses return values (PNG paths, a contact sheet, measured layout problems), a call limit ('Up to 24 per call'), and sweep behavior. Yet it does not explicitly confirm read-only safety or mention where generated PNGs are stored or whether they persist, leaving side-effect and safety context incomplete for a tool that writes files.

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 dense paragraph that front-loads the main action and key constraints. It is efficient but slightly run-on; every sentence provides value, though the parenthetical examples could be formatted more scannably.

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 the complexity (3 parameters, one with a non-trivial format), no output schema, and no annotations, the description covers the essential return values and sweep behavior. It is nearly complete but omits explicit safety/read-only notes and handling for empty 'times', which would fully close the gap.

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%, so the description must compensate. It thoroughly explains the 'times' parameter format with examples ('seconds or Times like "line:3", "clip:c2+0.5", "end-1"') and the 'sweep' parameter's effect. The 'project' parameter is only implicitly described through context, but the complex parameter is well covered.

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 states a specific verb ('Render stills') and resource ('at the given moments straight from the project'), and explicitly distinguishes itself from the sibling 'render' by clarifying 'no full render' and 'no film is made'. An agent can immediately understand this is a lightweight preview tool versus a full render.

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?

It clarifies that no full render occurs and contrasts with 'render' by describing the sweep mode as doing what render does before encoding but without making a film. This gives clear context for when to choose preview over render. However, it does not explicitly mention when to use this versus other siblings like 'check' or 'review', leaving some alternatives unaddressed.

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