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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false, destructiveHint=false. The description adds useful behavioral context beyond the annotations: it discloses the output shape ({ ok, packageName, apks: [{ path, sizeBytes, role }] }) and the downstream constraints (5MB default pull cap, 20MB max). It does not mention authentication or permission requirements, but for a read-only path listing that's minor.

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 and mechanism, then behavior details, then return shape. No waste; every sentence adds distinct 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?

No output schema exists, so the description compensates by fully specifying the return object. It covers the action, the split-APK nuance, downstream usage with device_file_pull, and size limits. Nothing an agent needs to call it correctly is missing.

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 coverage is 100% and both parameters (udid, packageName) have descriptions in the schema. The description mentions packageName implicitly through 'an installed app' but adds no additional semantics beyond what the schema provides. Baseline 3 is appropriate when the schema does the heavy lifting.

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 (List), a specific resource (APK file paths for an installed app), and notes the mechanism (`pm path`). The description also notes it returns base + split APKs, which clearly distinguishes it from device_list_apps (lists installed apps) and device_file_list (lists directory contents).

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?

Explicitly tells the agent what to do with the results: "use device_file_pull on individual paths to fetch the bytes (default 5MB cap, raise via maxSizeBytes up to 20MB)". It names the alternative for a subsequent step but doesn't explicitly state when this tool should NOT be used (e.g., when you only want metadata vs. bytes). Clear context, no exclusions.

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