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

Goes well beyond the annotations: it discloses that the prior version is retained for undo (important context given destructiveHint=true), that transcription incurs a charge and an extra `pipelines:run` scope, that the tool requires `pipelines:write`, and that a call is capped at 25 actions. It also separates saving from rendering, which the annotations cannot express.

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?

Dense but front-loaded — the core statement comes first, then mechanics, cost, undo, and the render hand-off. Every sentence carries information, though the parenthetical cost/scope clause and the slightly tangled past tense in "the names get_project listed" cost some readability.

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 mutation tool with no output schema, it covers scope, cost, limits, undo, and the follow-up render step, which is nearly everything an agent needs. The one meaningful omission is what happens when one action in the ordered list fails — whether earlier actions persist.

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 100% and already contains an example, so the baseline is 3; the description still adds real meaning by saying action names come from `get_project`, that each entry carries that action's own arguments, and that actions are applied in order. It does not explain failure/atomicity semantics for a partially invalid action list, which is the remaining semantic gap.

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 verb and resource ("Change a timeline project") and immediately clarifies that the change is expressed as an ordered `actions` array. It distinguishes itself from `render_project` ("Saving is not rendering") and `undo_project_edit` (the previous version is kept for it), so an agent can place it among siblings without opening the 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 concrete routing rules: follow with `render_project` when the user wants the corrected video, rely on `undo_project_edit` to revert, and add a `transcribe` action after a trim so captions track the new cut. It also works a worked example ("the narration is two seconds too long" is one trim_clip). It does not state when to prefer this over `edit_asset` or `create_editor_project`, leaving that to name inference.

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