Upload texttrack

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

Annotations already declare this is a non-read-only, open-world, non-idempotent, non-destructive write. The description adds a genuine behavioral fact not present in structured fields: the required upload scope, which tells the agent about an auth prerequisite. It does not mention duplicate-language handling or reversibility, so it stops short of a 5.

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?

Two short sentences, zero filler, and the core action is front-loaded ahead of the auth requirement. Every sentence earns its place.

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 6-parameter mutation tool with full schema coverage and no output schema, the description covers purpose, input format, and auth requirement adequately. It omits what happens if a track already exists for the language and whether the new track becomes active by default, which would round out the picture.

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%, with every parameter (including the captions/subtitles enum and the WebVTT format) documented in the schema itself. The description only restates that WebVTT content is supplied, adding no syntax or constraint detail beyond the schema, so the baseline of 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?

The description uses a specific verb+resource ('Add a caption or subtitle track to a video') and names the input format (WebVTT). It implies the additive distinction from update_texttrack via 'Add', but does not explicitly name or rule out sibling operations, so it falls short of a 5.

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 a concrete prerequisite ('Needs the upload scope'), which is useful context for when this call will succeed. However, it offers no guidance on when to use this versus update_texttrack/delete_texttrack, nor any exclusions or alternatives, leaving usage implied rather than spelled out.

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