diff_since

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

No annotations are provided, so the description carries the full burden, and it does disclose the return shape in unusual detail (what counts as changed, the tolerance threshold, the topology and material_slots payloads). It doesn't state whether a missing/expired checkpoint is an error or what happens with the default `name`, which keeps it short of a 5.

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 the core answer (what changed), then the detail on payload contents, then a closing usage line. No filler and no repetition of the tool name.

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 and no annotations, the description does the heavy lifting by describing the returned fields, which is enough for an agent to consume results. The remaining gap is the checkpoint-identification parameter and error behavior when no checkpoint matches.

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 0%, so the description must compensate. It does explain `tolerance` meaningfully (metres of movement/size change required to count as changed), but the `name` parameter and its default "last" are never explained — it is only implied that it identifies a checkpoint.

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 operation (diff against a checkpoint) and enumerates exactly what it reports: added/removed objects, moved or resized objects, plus topology and material_slots deltas. This is distinguishable from siblings like checkpoint, rollback, status, or mesh_info, which perform different jobs.

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?

"Use it to review a long session or to see what a tool did" gives clear positive guidance on when this tool applies. It stops short of naming exclusions or pointing at alternatives (e.g. status vs checkpoint vs rollback) for related questions.

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