plasticity_create_instance

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

Annotations declare the safety profile (readOnly=false, destructive=false, openWorld=false), and the description adds a genuinely non-obvious behavioral trait: the instance stays linked so later source-body edits propagate. That linkage-vs-static-copy distinction is real value beyond the annotations. No auth or rate-limit context, but none is clearly needed for a local CAD mutation.

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 tightly written sentences, zero filler, with the core action front-loaded and the propagation caveat placed where it matters. Every clause earns its place.

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 4-param mutation tool with an output-schema-free surface, the description covers the key behavioral trait but leaves two parameters (intent, revision) undocumented and says nothing about what is returned. Adequate but with clear gaps against 0% schema coverage.

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% across 4 parameters, so the description must carry the burden. It only clarifies translationMm ("optionally translated in millimeters") and obliquely bodyId; the required "revision" and the "intent" parameter are never mentioned or explained anywhere.

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?

Specific verb+resource: "Create one native linked instance from a current source body." The qualifier "native linked" distinguishes it semantically from plasticity_duplicate_bodies (which makes independent copies), but the description never names that sibling or explicitly routes between them, so it falls short of a 5.

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?

The propagation clause ("Later source-body edits propagate through the instance") implies when to prefer this over a static duplicate, but it never states when-not to use it or names alternatives (duplicate_bodies, realize_instances, list_instances). Usage is inferable rather than instructed.

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