mate_faces

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

With no annotations, the description carries the burden well: it explains the geometric effect, the sign convention for offset, the exact-one-face constraint, and optional rotation about the contact normal. It omits persistence/undo behavior and explicit error behavior when a face spec matches zero or multiple faces, keeping it from 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?

Three sentences, front-loaded with the core operation, then constraints and the optional rotation. Every sentence adds useful information without repetition or padding.

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 relatively complex assembly-mating mutation with no annotations and an output schema, the description covers most call-critical behavior. It leaves the doc parameter and some operational prerequisites/error cases implicit.

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 must compensate. It explains the roles of moving and fixed, the units and sign meaning of offset, the face-spec requirement and pointer to list_faces, and the effect of rotate_about_normal_deg; the doc parameter remains unexplained.

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 states a specific operation on a specific resource: moving an object so one planar face lies against another object's planar face. It clearly separates this from a generic transform or coaxial mate by specifying planar-face contact, normal orientation, and centre alignment.

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?

It implies the tool is for planar face mating in an assembly and points to list_faces for resolving face specs. However, it does not explicitly say when to use this instead of mate_coaxial or transform, nor does it state prerequisites or exclusions.

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