video_add_text

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

With no annotations, the description carries full burden. It details parameter behavior (shadow, start_time, duration, CRF, preset) and explains output_path auto-generation. However, it does not explicitly state whether the tool modifies the original file or creates a new one, missing a key behavioral aspect.

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 begins with a clear one-line summary and uses a well-structured list for parameters. While slightly verbose, it is organized and front-loaded. Every line serves a purpose.

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 12 parameters with 2 required, the description explains all parameters sufficiently. An output schema exists, so return values are covered. Missing are potential side effects or prerequisites, but overall it is complete enough for effective use.

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%, yet the description provides thorough explanations for all 12 parameters, including examples for 'position' (named, pixel, percentage). This adds significant value beyond the schema, fully compensating for the lack of schema descriptions.

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 clearly states 'Overlay text on a video (titles, captions, watermarks).' It uses a specific verb ('overlay') and resource ('text on a video'), and distinguishes from sibling tools like 'video_add_texts' (plural) and 'video_subtitles'.

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 does not provide any guidance on when to use this tool versus alternatives, nor does it mention when not to use it. There is no explicit context for selecting this tool among the many video siblings.

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