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

With no annotations, the description carries the full burden. It usefully discloses the auto-creation of an overlay track and the preset/text override precedence, but says nothing about permissions, failure behavior, or what is returned for a mutation of this size.

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?

Four tight sentences, front-loaded with the core action and then the preset/custom choice and the track side effect. No filler, though the parenthetical preset list is dense.

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 42-parameter mutation with no annotations and no output schema, the description covers the primary workflow adequately since the schema documents all parameters. It is still thin on behavior (no return value, no permissions/error context) given the complexity.

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, but the description adds genuine meaning the schema lacks: the presetId-to-style mapping, the fact that text overrides the preset default text, and the presetId-or-textConfig alternative. That interaction between parameters is not expressed anywhere in the schema.

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 a text overlay to the video timeline'), which clearly separates it from media/audio/remotion overlay siblings. It does not name a sibling explicitly (e.g. add_media_overlay), so it stops short of the 5-level 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?

It gives the two invocation routes (presetId vs custom textConfig) and enumerates the preset IDs, which is helpful. However it never states when to use this tool versus siblings like add_media_overlay, update_overlay_item, or add_overlay_track, and gives no exclusions or prerequisites.

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