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

Annotations already carry the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds value beyond them: the exact payload shape, the meaning of the `actions` field as the accepted edit vocabulary, unit disclosure ('Times are in seconds'), and the hard prerequisite on id provenance. It does not mention behavior when projectId is invalid, which keeps it at 4.

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 sentences, front-loaded with what is returned, then the dependency rule, then the units caveat. Every clause carries distinct information and nothing is repeated from structured fields verbatim.

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?

With no output schema, the description must convey the return shape and it does so concretely (tracks, clips, trim points, volume, fades, actions with their arguments, seconds as the unit). Only minor gaps remain, such as failure behavior for a bad projectId, which is low-risk for a read-only tool.

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 the single parameter already documents its provenance ('From list_projects or open_run_in_timeline'). The description reinforces that ids come from this call for edit_project but adds no new syntax or constraint on projectId, so the baseline 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?

States a specific verb and resource ('Read one timeline project') and immediately enumerates the returned structure — tracks, clips, start/end, trim points, volume, fades, and `actions`. This is clearly distinguishable from list_projects (many) and get_project_render (render artifacts).

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 an explicit ordering rule — 'Always call this before edit_project: clip and track ids come from here' — which is exactly the guidance an agent needs for a read-before-write workflow. It does not name an exclusion case (e.g. when list_projects is sufficient instead), so it falls just short of a 5.

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