Check whether a path is a file or folder in the executor workspace (UNC isfile/isfolder)

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

Goes well beyond the read-only/idempotent annotations: it names the required UNC functions, explains that each probe is type-guarded and pcall-wrapped independently so a missing/erroring function reports false, and specifies the exact error object when neither is available. This is exactly the runtime behavior an agent cannot infer from 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-loaded with the core behavior and the critical executor-vs-game warning, then structured metadata. It is somewhat verbose, repeating read-only/safety twice and echoing the signature already in the schema, but every section carries usable 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?

With no output schema, the description fully documents the return shapes ({ path, isFile, isFolder } or { error }) and the error case. Prerequisites, capabilities, and failure guidance are all present, so an agent has everything needed to invoke and interpret it.

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 path, timeoutMs, and threadContext, making the baseline 3. The description reinforces that path is workspace-relative and repeats the signature, but adds no format or constraint detail beyond the schema.

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+resource ('probe a path ... report whether it is an existing file and/or folder') and scopes it precisely to the executor's workspace, explicitly distinguishing it from the Roblox game. This differentiates it cleanly from siblings like verify-path-exists and read-file without needing the schema.

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 clear context for when this applies ('executor-side file I/O ... path is relative to the executor's workspace directory on the host machine, NOT the Roblox game') and prerequisites ('active-client, resolved-target'). It does not name the sibling tools (e.g. verify-path-exists, list-files) that a user might confuse it with, so it stops short of a 5.

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