read video playback metadata

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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real behavior the annotations cannot: the signed-in-user requirement and the exact API-key degradation payload ({supported: false, metadata: null}), plus null/omitted field semantics and an instruction never to guess unmeasured values. The only minor gap is that it does not describe pagination/caching or error behavior, but for a single-object read this is close to complete.

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?

Front-loaded with the core action and the returned-field list, then use case, then alternatives, then caveats — a logical progression with no filler. The long inline field enumeration is somewhat redundant given an output schema exists, which keeps it below a 5.

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 one-parameter, read-only tool with an output schema and full annotation coverage, the description supplies everything an agent needs: purpose, the frame-conversion use case, sibling routing, auth/degradation behavior, and null semantics. Nothing material is missing.

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?

There is a single assetId parameter with 100% schema description coverage (UUID, sourced from assets_list or assets_get), so the schema already carries the semantics. The description only implies single-asset scoping via 'Read one asset's' and adds no format or sourcing detail beyond the schema; baseline 3 is appropriate.

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?

Starts with a specific verb+resource ('Read one asset's measured playback metadata') and enumerates exactly what comes back (duration, fps, frameCount, dimensions, codec, proxy fields, thumbnailsManifestUrl). It also carves itself apart from siblings assets_get and assets_get-download-url, so an agent can pick it without opening a schema.

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?

Gives a concrete positive use case ('convert between seconds and frames for frame-accurate edits such as lipsync_create-timeline clips') and explicitly routes the agent elsewhere for name/media url (assets_get) and file download (assets_get-download-url). It also states negative scope: it does not analyze media, read transcripts, or change the asset.

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