caption_video

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

With no annotations, the description carries the burden and does meaningful work: it discloses that the video stays local, that cloud minutes are consumed, that a plan tier (Creator/Pro) is required, and it enumerates the returned fields. It stops short of stating failure modes (e.g. what happens if minutes run out) or time cost of rendering.

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?

Three dense sentences, front-loaded with the purpose and side effect, then return values and plan gating. Everything earns its place, though the enumerated output-format list partially duplicates the schema's output parameter.

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?

There is no output schema, and the description compensates by naming exactly what is returned (file, duration, engine, cloud minutes, studio link). With 13 parameters all documented in the schema and the privacy/plan constraints stated, an agent has everything needed to call it correctly.

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 per-parameter meaning is already fully documented, including the nuanced engine, output, and out_path descriptions. The description restates the choice of output formats and the default filename convention but adds no syntax or constraint detail beyond the schema, so baseline 3 applies.

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 ('Captions a local video or audio file') plus the exact renderer, output formats, and side effect of writing a file next to the input. It is clearly distinguishable from the sibling transcribe (which would just produce text) because burning in captions/overlays is called out explicitly.

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?

Usage is implied by the description (local file on this machine, captioning outputs), but there is no explicit when-to-use rule and no routing against the siblings. An agent gets no statement such as 'use transcribe instead when you only need the transcript' or 'use studio_link to fine-tune after rendering'; the list_styles pointer lives in the schema, not the description.

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