Add a raw feature

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

Annotations only provide a title, so the description carries the behavioral burden. It discloses that the tool posts a raw BTM payload (a low-level, hand-written operation), and the 'validate' parameter description adds that it re-reads the feature list and fails on regeneration errors. It does not explicitly state that this is a mutating operation, but 'Post' and 'add' clearly imply it. The escape-hatch framing also warns the agent this is advanced usage. Minor gap: no mention of auth requirements or failure modes beyond validation.

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 sentences, zero filler. The core action and the escape-hatch purpose are front-loaded, and the prerequisite sibling is named in the same breath. Every word earns its place.

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 low-level raw-payload tool with no output schema, the description gives the essential context: what it posts, where, when to use it, and what to read first. The validate parameter's behavior is documented in the schema. It could add a note about the response shape or error behavior, but the escape-hatch framing plus the prerequisite pointer is enough for an agent to invoke it 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 100%, so the schema already documents all five parameters. The description adds context for the 'feature' parameter by calling it a BTM payload and mentioning the BTFeatureDefinitionCall-1406 envelope, which is genuinely useful beyond the schema. However, the description does not explain the doc/ws/elem URL-segment pattern beyond what the schema already says, so the added value is modest. Baseline 3 is appropriate.

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 verb ('Post'), a specific resource ('a hand-written BTM feature payload to a Part Studio'), and explicitly frames it as the escape hatch for feature types with no dedicated tool. This clearly distinguishes it from the many sibling feature-creation tools (extrude, hole, fillet, etc.) and from onshape_update_feature/onshape_delete_feature.

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 description explicitly says when to use it: for feature types this server has no dedicated tool for. It also names the prerequisite sibling, onshape_get_feature_specs, telling the agent to read that first. This is strong routing guidance that prevents misuse of the raw-payload tool when a dedicated tool exists.

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