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

Annotations already declare this as a non-read-only, idempotent, non-destructive write. The description's added value is the phrase 'Revision checked', which signals optimistic-concurrency failure behavior beyond the schema, and the default-preview behavior. However, it does not explain what a revision conflict looks like or what the dry run returns, so the added context is thin against a mutation tool.

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 with the core action and the placement constraint front-loaded, followed immediately by the two behavioral caveats. No filler or restated title.

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?

An output schema exists, so return values need not be described, but for a nine-parameter, fully-required mutation the description stops short of covering layer semantics, duration handling, or the idempotency key's role. It is adequate as a headline, not complete as a spec.

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 only 22% across nine required parameters. The description maps loosely to assetId, startSeconds, expectedRevision and dryRun, but layerIndex, durationSeconds (nullable), workspaceId, projectId and especially idempotencyKey receive no semantic explanation in either the description or the schema, leaving the agent to guess at stacking and deduplication behavior.

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 names a specific verb (Insert) and enumerates the asset kinds it accepts (workspace image, generated shot, audio asset) plus the placement target (an explicit project time). That is enough for an agent to distinguish it from generic clip/media siblings, though it does not explicitly contrast with timeline_media_add or timeline_audio_add, which overlap on the 'put media on the timeline' intent.

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?

'dryRun previews by default' implies a preview-then-commit workflow, which is useful usage context, but the wording is terse and relies on the agent inferring that the first call should be a dry run. There is no explicit when-to-use or when-not-to-use guidance relative to the many adjacent timeline/clip tools in the sibling list.

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