Observe the live world and build semantic entity handles

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

Despite annotations already covering the safety profile, the description adds substantial behavioral context: it discloses that handles are retained in getgenv().__mcp_world_brain via weak references and structural fingerprints, that the walk uses GetChildren with hard caps, and that it 'never starts frame loops or performs an unbounded GetDescendants scan.' This goes well beyond the annotations.

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 core purpose well, but the body is dense jargon and the 'Signature' restatement plus the long 'Produces:' enumeration duplicate what the schema and annotations already convey, adding bulk without proportional value.

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 no output schema, the description carries the return-value burden and does so reasonably: compact evidence, GetFullName paths, bracket-safe expressions, positions/distances, scan/truncation counts, and session handles. It also covers failure guidance ('inspect tool-schema') and a verification path, making it nearly complete, though the return shape remains somewhat terse.

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 each parameter is already documented in the schema with defaults, ranges, and meaning. The description merely restates the signature without adding new semantics 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?

States a specific verb and scope ('Perform one bounded, read-only Luau observation') and enumerates exactly what it fuses: character rig, camera, PlayerGui, nearby parts, ClickDetectors, ProximityPrompts, TouchTransmitters, and Tools. This is clearly distinguishable from siblings like get-instance-tree or search-instances because it fuses multiple domains into a session handle model.

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 prerequisites ('Requires: active-client'), phase ('Phase: observe; cost=medium'), and a follow-up route ('Verify with: resolve-entity'). It does not, however, explicitly contrast when to prefer this over siblings such as get-instance-tree or discover-character, so a 4 rather than a 5.

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