Look up the Roblox engine API

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

Annotations already provide readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds value beyond annotations by stating it is 'authoritative' and 'live,' and by disclosing the exact nature of the data (parameter types, security level, deprecation, thread safety). It does not mention rate limits or output truncation, but those are less critical given the read-only nature.

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 with no filler. The first sentence front-loads the core purpose and output details, and the second immediately gives concrete use cases. Every clause adds value, and the structure is efficient and easy to parse.

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?

The tool is moderately complex (5 params) but the schema covers 80% and the description explains the return content thoroughly. Since there is no output schema, the description partially compensates by enumerating the kinds of members and metadata returned. It does not describe the output structure in detail, but that is a minor gap given the tool's read-only, lookup-oriented nature.

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?

The schema description coverage is 80%, meaning the schema already documents most parameters thoroughly (e.g., the 'name' parameter explains its multi-format acceptance). The description does not add additional parameter-level detail beyond what the schema provides, so it does not need to compensate. It meets the baseline for high coverage without adding redundant information.

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 ('lookup') with a clear resource ('live Roblox API dump') and enumerates the exact kinds of information returned (properties, methods, events, callbacks with parameter types, security level, deprecation, thread safety). It is clearly distinct from sibling tools like search_creator_docs and search_devforum, which are documentation searches rather than authoritative signature lookups.

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 lists when to use the tool: 'confirm a method exists, check whether it is deprecated or server-only, or find the right member name before writing Luau.' It does not explicitly name alternatives or say when NOT to use it, but the use cases are precise and the distinction from sibling search tools is implicit through the 'authoritative' and 'live' qualifiers.

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