fit

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

With no annotations, the description carries the full burden and meets it: it discloses the side effect of saving a new version, the limited view-based scope, what stays fixed, how max_step and stiffness affect behavior, the return payload (diff images, IoU before/after, every change), and revert support. There is no annotation contradiction.

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?

The description is dense but every clause earns its place. It front-loads the core action, then packs operational details about scope, locking, parameters, constraints, and return values without fluff or repetition.

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 an 11-parameter tool with no annotations and no output schema, the description is unusually complete: it covers preconditions, parameter effects, scope, outputs, and undo. The only notable gap is the unexplained align parameter, but an agent could still use most advanced functionality safely.

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 0%, so the description compensates well: it explains allowed params values (pos, r, offset, size), only/lock name syntax, max_step units, stiffness as a spring toward starting values, and the against options. However, the align parameter is not explained, and name/iterations/resolution are only inferable from their titles.

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 opens with a concrete verb-resource-result: 'Auto-fit the model to its reference silhouettes and save the result as a new version.' It then specifies exactly what moves (joints, radii, blob offsets, blob sizes), making it clearly distinct from sibling tools like measure, compare, or check.

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 actionable guidance such as 'Block out the body plan by hand first: fitting is local and can't fix a missing or misplaced limb' and explains the against options (refs, plan, auto). It does not explicitly name alternative sibling tools or state when not to use this tool, so it stops short of full routing guidance.

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