feature_thread

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

With no annotations, the description carries the full behavioral burden and does so thoroughly: default auto-recommendation of designation from cylinder diameter (10 mm -> M10x1.5 6g), what happens when thread_class is omitted, the units default, and precise failure modes (INVALID_PARAMS with nothing changed, FUSION_API_ERROR with timeline rollback). This is exactly the mutation-safety information an agent needs.

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 purpose is front-loaded, followed by defaults, then errors, returns, and examples in a scannable order. It is dense but nearly every sentence carries operational information; the returns block is long but necessary since no output schema exists.

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 an 11-parameter mutation tool with no annotations and no output schema, the description covers defaults, auto-selection rules, error semantics, and an explicit return structure. Nothing material is missing for 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 coverage is 100%, so the baseline is 3, but the description adds meaning beyond the schema: it explains the auto-recommendation logic for designation/class, the interaction rule that length requires full_length=false, and points to feature_thread_options as the source of valid strings. Minor gap: it doesn't clarify offset/location behavior in more depth than the schema already gives.

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 ('Add a cosmetic (default) or modeled thread to cylindrical faces') and scopes it to bolts, shafts and tapped holes. The distinction from feature_thread_options is clear: that sibling lists names, this one applies a thread.

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 guidance on when to override hole/shaft detection and when to consult feature_thread_options for valid type/designation/class strings, plus two worked examples. It lacks an explicit statement of when not to use it (e.g. vs feature_hole when no hole exists yet), but the usage context is otherwise clear.

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