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

With no annotations, the description carries the full burden and does disclose key behavior: transcription happens on first use, results are cached on the video until the file changes, refresh overrides the cache, and a Viewer role is required. It omits failure/edge behavior (e.g., videos with no audio or unavailable transcripts), which keeps it below 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?

Four short sentences, each earning its place: return shape first, then caching/refresh behavior, then the span hint, then the permission requirement. Nothing redundant and the most decision-relevant information is front-loaded.

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 read tool with no annotations and no output schema, the description covers return shape, caching, span control and auth. It is largely complete; only edge-case behavior for videos without transcribable audio is unaddressed.

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% and all six parameters are documented there, including the flexible time format for start/end and the refresh semantics, so the schema does the heavy lifting. The description restates the start/end span idea and adds caching context but no syntax or defaults 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?

States a specific resource (the transcript of a video in a video surface) and the return shape (timestamped segments), so the agent immediately knows this is a transcript-retrieval tool rather than a video-metadata tool like list_videos or watch_video. It does not explicitly name a sibling it must not be confused with, so it stops 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?

Usage is implied rather than instructed: the agent can infer it should call this when it needs spoken content, and the description notes start/end for spans and the Viewer role prerequisite. There is no explicit when-to-use/when-not or pointer to list_videos for resolving video_id (that hint lives only in the schema).

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