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

Annotations already declare non-readOnly, non-destructive, non-openWorld, so safety is covered; the description adds real behavioral context about how overlapping balls blend and how radii interact with the resulting surface. It does not say that a new object is created, how it is named, or what resolution/threshold do to output density.

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?

Three tight sentences, front-loaded with the technique, then use cases, then the one non-obvious parameter rule. Nothing is padding and the sizing advice is actionable.

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?

A five-parameter generative tool with no output schema and no schema descriptions needs more than this: the effect of threshold and resolution on the result is never explained, and the description never states what is produced (a new named object) or whether it replaces existing geometry.

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 carries the full burden. It usefully clarifies that radii is one value per point (the key mapping between the two parallel arrays), but leaves name, threshold, and resolution — the latter two defaulting to 0.6 and 0.05 with no explanation of their effect on the mesh — entirely undocumented.

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 ("make one smooth organic mesh from overlapping balls (metaballs)") and explains the defining mechanic: the balls merge into a single skin. It clearly separates itself from hard-surface siblings like create_primitive or loft by naming the metaball technique, though it never names a sibling explicitly.

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 concrete when-to-use context ("Good for hands, clouds, bushes, rocks, creature bodies") plus a practical sizing rule ("use radii a bit larger than the surface you want"). It stops short of when-not-to-use or pointing to an alternative tool for hard-surface or single-primitive work.

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