Add a raw 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 behavioral burden. 'Post' reveals it is a mutation, but there is no mention of permissions/auth needs, that a raw payload bypasses the safety of typed mate tools, what happens to the assembly on partial failure, or the practical consequence of the schema's 'validate' default (a re-read that fails the call on regeneration error). For a low-level write escape hatch, that is a significant gap.

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?

A single sentence, front-loaded with the action and closed with the routing rule. Nothing redundant, nothing padded.

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?

With five parameters, a free-form nested 'feature' object (additionalProperties), no output schema, and no annotations, the description is too thin: it does not say where a valid payload comes from (e.g. onshape_get_assembly_features), what the response returns, or what 'validate' failure means in practice. An agent could not confidently construct a correct call from this definition alone.

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 100%, so doc/ws/elem and the 'validate' semantics are already documented in the schema; baseline 3 applies. The description adds only the phrase 'hand-written payload', hinting that 'feature' is unvalidated free-form JSON, and gives no hint about where to obtain a valid payload shape.

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 action (post a hand-written assembly feature payload) on a specific resource, and the phrase 'escape hatch for mate types with no tool here' implicitly distinguishes it from the sibling mate tools (onshape_assembly_mate, onshape_assembly_relation) and from onshape_update_assembly_feature. It never names those siblings explicitly, so the differentiation is inferential rather than declarative.

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 escape hatch for mate types with no tool here' signals the when-to-use condition (only when no dedicated tool covers the mate type), which is genuine routing guidance. However, no alternative is named, no prerequisite is given (does the element need to be an assembly tab?), and there is no when-not-to-use statement beyond the implication.

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