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

With no annotations, the description carries the full burden but discloses no side effects, permissions, or behavioral traits. It does not mention that a track is auto-created (per schema), nor what happens to existing overlays, how mutations are reversible, or any auth requirements.

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 sentence that front-loads the core purpose and then enumerates capabilities. It is efficient and contains no filler, though the long feature list is a minor detraction from crispness.

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 26-parameter mutation tool with nested objects, no annotations, and no output schema, the description is far too thin. It should cover required parameters, track auto-creation, side effects, and return behavior, but only lists high-level feature categories.

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 100%, so the baseline is 3. The description enumerates feature categories (transform, border radius, shadow, etc.) but adds no syntax, defaults, or meaning beyond what the schema already provides for each parameter.

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 ('Add') and resource ('image or video media overlay') scoped to the 'edit timeline'. It clearly distinguishes itself from siblings like add_text_overlay, add_audio_track, and add_remotion_overlay by specifying the media type.

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?

Provides no when-to-use guidance, no alternatives, and no prerequisites. It lists capabilities but never says when to choose this tool over add_text_overlay or add_remotion_overlay.

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