Update an assembly feature

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

Annotations carry only a title, so the description bears the full burden. It does disclose the key behavioral fact that this is a full replacement ('Replace ... payload', 'the whole feature JSON'), implying omitted fields are dropped, but it never says so outright, nor does it mention downstream regeneration, permissions, or reversibility.

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?

Two dense sentences with no filler; the replacement semantics lead and the envelope/format requirement follows. Every clause carries information the caller needs.

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 mutation tool with no output schema and thin annotations, the description covers the hard part: where the payload comes from and how it must be shaped. The gaps are the consequences of an incomplete payload (silent reset of unspecified fields) and validation/regeneration behavior, which the validate parameter only partly covers in the schema.

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 baseline is 3, but the description adds genuine meaning for the free-form `feature` object: it must be the complete feature JSON as returned by onshape_get_assembly_features, wrapped in a BTFeatureDefinitionCall-1406 envelope. That envelope requirement is invisible in the 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?

States a precise verb (Replace) and resource (an assembly feature's payload) and enumerates the concrete cases it covers (mate type, connectors, limits, relation ratio). An agent can tell this is the assembly-feature mutator rather than the part-studio onshape_update_feature, though no sibling is named 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?

The instruction to post the whole feature JSON 'e.g. as onshape_get_assembly_features returns it' gives a real workflow entry point — fetch, then replace. But there is no guidance on when to prefer this over onshape_set_mate_values, onshape_assembly_add_feature, or onshape_assembly_mate, nor any exclusion for partial edits.

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