Distinguish newcclosure wrappers from native C closures

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely new context (cost=medium, phase=observe, output kinds) that annotations do not carry. However 'Produces: created-handle' sits in tension with the read-only/idempotent hints, since creating a handle implies state mutation, and this is left unexplained.

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 content is short but poorly front-loaded: the leading sentence is an alias note rather than the tool's purpose, and the body is a cryptic key=value metadata dump (phase, cost, idempotency, capabilities, produces). The agent has to parse boilerplate before reaching anything actionable, and the 'On failure' sentence just redirects to another tool.

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, so the description must convey the return value, but it only says 'Produces: structured-observation, created-handle', never stating that it returns a boolean-style classification or how the wrapper verdict is expressed. It also omits any differentiation from the cluster of sibling is-* closure predicates, leaving the agent without the context needed to pick this tool 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% and both parameters (functionPath, threadContext) are fully documented in the schema, including the Luau-expression meaning of functionPath and the default behavior of threadContext. The description merely restates the signature types and adds nothing beyond the schema, so the 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?

The description never actually states what the tool determines (whether a function is a newcclosure wrapper); that meaning lives only in the title. It opens with invocation mechanics ('Call isnewcclosure with the iscustomcclosure alias') and 'Capabilities: debug closure primitives', which hint at purpose but do not distinguish it from the many sibling predicates (is-c-closure, is-l-closure, is-executor-closure, new-c-closure). An agent must fall back on the title to understand the tool.

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?

It gives preconditions ('Requires: active-client, resolved-target') and a phase tag ('observe'), which is implied usage context. However it offers no guidance on when to choose this predicate over its close siblings like is-c-closure or is-l-closure, and no when-not conditions. Usage is only implied.

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