feature_instantiate

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

With no annotations, the description carries the full burden and does so well: it discloses up-front validation of {refs, inputs}, resolution against the host's CURRENT geometry, that unresolved tags/interfaces 'fail loudly', and a deterministic build that also runs publish_interface and declare_intent as side effects. This is exactly the behavioral context an agent needs before invoking a mutating tool.

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?

Purpose and behavior are front-loaded in the first sentence, followed by a compact parameter glossary. Dense with parentheticals and an issue reference, but every element is informative and nothing is wasted.

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?

Despite no output schema, the description spells out the return shape ({template, schema, host, refs, inputs, handle, name, interfaces, intent}) and the composed side effects. Combined with validation and failure-mode notes, an agent has everything needed to call and interpret the tool correctly.

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 does: template (registered name, browsable via feature_list), host (body handle), refs (interface name / f_ / e_ tag / literal {origin, z_axis?, x_axis?} frame), and inputs (typed, unit-bearing, range-checked scalars). All four parameters gain meaning beyond the bare schema.

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 ('stamp') plus resource ('registered FEATURE TEMPLATE') with two concrete examples (mounting_boss onto seat frame, bolt_pattern onto f_ face tag). It clearly distinguishes itself from sibling feature tools (feature_list, feature_schema, feature_validate) by describing a build action rather than a browse/validate action.

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 clear usage context: a template must be registered, and it routes the agent to feature_list to browse templates. However, it never explicitly states when NOT to use this versus alternatives like feature_validate or family_materialize, so the comparison is implied rather than spelled out.

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