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

Annotations declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, so the safety profile is already given. The description adds useful scoping context ('acts only on the explicit project_id and returns the project identity with its result'), but does not explain what non-read-only state change actually occurs, which is the gap the false readOnlyHint leaves open. No contradiction with annotations.

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?

Roughly 50 words with no filler, and the PROJECT-SCOPED constraint is correctly front-loaded. The dense telegraphic style trades readability for brevity, but every clause carries content.

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 9-parameter, non-read-only tool with no output schema and 11% schema coverage, this description is too thin. It leaves the mutation semantics, most parameter meanings, and the distinction from near-neighbor tools unexplained, so an agent lacks enough to invoke it confidently.

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 only 11% (project_id alone is documented), so the description must compensate. It does implicitly name several parameters - t ('at t'), box/points ('its box (or points)'), the start/end window ('<=6 s'), depth ('hides behind it'), and an object reference ('object:<id>') - but the mappings are cryptic and 'label' and 'id' semantics remain unclear.

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 does give a specific action ('Segment an object through a window') and a return shape ('its box (or points) at t'), so it is more than a restatement of the name. However, the phrasing is heavily jargon-laden ('fx object', 'program fractions from look_at') and never plainly states what selecting an object produces, leaving the boundary with siblings like look_at or track_point ambiguous.

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?

There is a partial constraint ('<=6 s' window) and references to related behaviors, but no explicit when-to-use vs when-not or alternative tool. An agent cannot tell from this text whether to reach for select_object, look_at, or track_point for a given segmentation task.

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