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

With no annotations present, the description carries the full transparency burden and does well: it discloses partial-update semantics ('Only the fields you pass are changed'), the null behavior of source_out_frame, and the workflow requirement to duplicate the layer first. It does not cover error cases, permissions, or reversibility, but the core behavioral traits of the mutating call are clearly communicated.

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 front-loaded with the core operation and is not bloated, and each section serves a purpose: operation, parameter summary, and usage guidance. The parenthetical field explanations partly duplicate the schema, but they are compact and help the agent quickly grasp the tool's intent without switching contexts.

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 mutating tool with no annotations and no output schema, the description is reasonably complete: it defines the operation, covers all trim-related fields, specifies partial updates, and provides a real-world procedure. It does not mention validation rules or failure behavior, but the provided context is sufficient for correct invocation in the common case.

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 100%, so the baseline is 3; the description adds value beyond the schema by clarifying the relationship between the three trim parameters and the intended workflow, especially the note that only passed fields are changed. It does not introduce new frame/fps details beyond the schema, but the usage context makes parameter behavior easier to internalize.

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 opens with a specific verb-resource pair: 'Patch a video layer's trim window,' making the tool's function immediately clear. It goes on to name the exact trim parameters and the intended use case, clipping a segment of a source mp4, which separates it from sibling tools like set_video_clip or cut_range.

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 gives concrete guidance on when to use the tool: to clip out a segment of a source mp4, with a clear prerequisite ('duplicate the layer first') and a strategy ('set disjoint source windows'). It does not explicitly name alternative tools or say when not to use them, so it stops short of a 5.

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