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

Beyond the readOnly/openWorld annotations, it discloses important behavior: the source is Facebook's caption track, auto-generated captions may be used, uncaptioned videos return `not_configured` (501), that case is not charged, and successful calls cost 1 credit. This is unusually rich context for invocation and failure handling.

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 return type and then adds operational details. The opening 'Video transcript. Transcript for...' is slightly redundant, but overall it is compact and every other sentence provides useful information.

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 transcript-fetching tool without an output schema, the description explains the return format, caption source, failure behavior, and billing. It is nearly complete, with the main remaining gap being semantics for the `language` and `cache_max_age` parameters.

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 67%, and the schema already documents `url` and `language`. The description reinforces that the URL must be a public Facebook video/reel URL, but it adds nothing about `language` or `cache_max_age`, so it does only partial work beyond 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?

The description clearly states the resource and return shape: a transcript for a public Facebook video or reel, as one text block plus timed cues. It is more specific than the title alone, but it does not explicitly differentiate itself from sibling transcript tools such as facebook_adTranscript or reddit_postTranscript.

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 clear usage context: works for public Facebook videos/reels that have a Facebook caption track, including auto-generated captions. It also states the key exclusion that videos without captions are not yet supported, though it does not name alternative transcript tools.

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