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

With no annotations provided, the description carries the full burden and does so well. It discloses the return fields, the effect of `depth` recursion, and especially error handling: unreadable entries come back as `type: null` with an `error`, so one bad child doesn't hide the rest—this is critical context not present in schema or 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?

Three sentences, front-loaded with the core action Scientific, then the two optional parameters, then error behavior. No fluff or repetition of schema details that are already clear. Every sentence earns its place.

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?

For a 4-parameter tool with no output schema, the description gives enough to call correctly: required params are implied by schema (udid, remotePath), optional params are explained precisely, and the return format is described. The error-handling behavior is a notable asset that fills the gap left by the absent output schema.

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 baseline is 3. The description adds meaningful nuance beyond the schema: it explains why `bundleId` matters (database, caches, logs) and clarifies that `depth` > 1 triggers recursion prepared—the schema says 'default 1 = the directory itself' but doesn't emphasize the recursion trigger. This is helpful but not exhaustive, so a 4 is appropriate.

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 opens with a specific verb and resource: 'List files and directories on an iOS device.' It clarifies what each entry returns (name, type, size, modification time) and immediately distinguishes the two browsing modes (app container vs. shared media), which sets it apart from generic file-listing siblings like device_file_list.

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 explicit conditional guidance: pass `bundleId` to browse an app's own container (and explains why that matters for app under test), omit it for shared media, and use `depth` above 1 to recurse. This tells an agent exactly when and how to invoke the tool, though it does not name alternative listing tools.

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