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

Annotations already declare a safe read profile, and the description adds genuinely useful context beyond them: 'Runs nothing. Pure standard library, no network or model' and the certificate is 'read but never verified.' The safety-critical nuance that signing is inspected but not validated is exactly the kind of disclosure an agent needs.

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?

A single dense paragraph with the input contract front-loaded and the return surface enumerated after. Every clause carries information, though the long enumeration of return fields is on the heavy side.

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 compensates by listing every returned artifact (package metadata, grouped permissions, exported components, host-grouped URLs, signer certificate fields). An agent knows precisely what to expect from a call.

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%, so the baseline is 3, but the description adds meaning by pinning the constraint to the decoded size ('at most 2,000,000 bytes') and calling out that input may be base64 or a data URL, clarifying the required 'file' param beyond the schema text.

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 ('Read') and resource ('.apk') and immediately enumerates exactly what it returns (package/version/SDKs, permissions, components, URLs, signer). It is distinguishable from generic siblings like inspect_binary and extract_strings because it specializes on Android APK structure.

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?

Usage is implied through the input contract (base64 APK, max size) but there is no explicit when-to-use/when-not guidance and no routing to alternatives such as inspect_binary or extract_strings despite their overlap with the string-table feature described here.

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