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

Annotations only declare a non-read-only, open-world, non-idempotent, non-destructive profile; the description goes well beyond that with the critical lifecycle trait that an opened skill "STAYS OPEN" and rides tool responses, that subskills are marked as opened, and that `release` (with "*") tears it down. It also discloses that `release` takes precedence over `name` and that the skill lives in the connected world, not the host.

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?

Front-loads the definition of a skill and then moves through the call modes in a logical order. It is dense and paragraph-length, with a few flourishes ("this tool is the only way to open one", "a skill is the already-correct path") that add emphasis rather than information.

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?

There is no output schema, and the description compensates by specifying what a list returns (name + one-line description + which are already open) and what opening returns (full instructions, dependency presence, exact tool names, subskills). For a 4-parameter, zero-required, dual-mode tool, nothing an agent needs before calling is missing.

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% and every parameter (`as`, `name`, `scope`, `release`) is already documented in depth, including the subskill "parent/sub" addressing and the enum values. The description restates the list-vs-open dual mode and release precedence without adding syntax or constraints the schema lacks, so baseline 3 applies.

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 — "Open an ENGINE skill" — and defines what a skill is ("a packaged procedure for one job in this world, carrying the instructions plus the assets, guides, and tools"). It also distinguishes itself from siblings by asserting it is "the only way to open one" and by contrasting with deriving a job "from first principles."

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 context for use: no-argument call to list, `name` to open, `release` when the whole job is done, and a clear routing rule — "Reach for this BEFORE working out a multi-step engine job from first principles." It stops short of naming sibling tools (guides, use_tool, describe_tool) or stating when NOT to use it.

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