set_material

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

With no annotations, the description carries the load and does substantively: it discloses the effect (mass/density change from the 1000 kg/m³ default), the return ("Returns mass properties including density"), custom-material behavior via density_kg_m3, and cross-language name resolution. It omits permissions, reversibility, and document-scoping, but the behavioral disclosure is richer than the schema alone.

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 core action and return are front-loaded and the examples earn their place. But the second and third sentences are garbled ("One SolidWorks does not have (say \"TPU\") comes with its density"), reading as truncated phrasing that forces the agent to reconstruct the meaning rather than stating it cleanly.

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?

Given a 3-param tool with no annotations and no output schema, the description covers the primary parameter, the density escape hatch, and the return value adequately. The undocumented `database` parameter and the slightly broken custom-material sentence leave the definition incomplete for full correct invocation.

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, and it does well for two of three params: it explains `name` (English names, cross-language) and `density_kg_m3` (custom material carrying only density). The third param, `database`, is never mentioned, leaving a real gap in an otherwise strong explanation.

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 ("Assign a material by name") with concrete examples ("6061 Alloy", "AISI 1020", "ABS") that make the resource unambiguous. It doesn't explicitly contrast with the nearby set_appearance sibling, but the operation itself is clear enough that an agent can distinguish them without opening a schema.

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 description implies when the tool is useful ("Makes mass and density reflect a real material instead of the 1000 kg/m³ default"), which frames the intent as obtaining realistic mass properties. However, it never names an alternative or says when not to use it (e.g. vs set_appearance, or vs leaving the default), so guidance remains implicit.

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