android_file_roots

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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds useful behavioral context beyond annotations: the roots are 'currently authorized' and the tool has no prerequisite of Accessibility or a file manager. This helps the agent understand prerequisites and dynamic state.

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?

The description is exactly two sentences with no filler. The primary purpose is front-loaded, and the additional prerequisite clarification is concise and valuable.

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 zero-parameter, read-only listing tool, the description is sufficient. It tells the agent what the tool returns conceptually, that no special prerequisites exist, and annotations cover the safety profile. No critical missing context prevents correct invocation.

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?

The tool has zero parameters, so there is no parameter meaning to elaborate. Baseline for zero-parameter tools is 4, and the description appropriately avoids inventing parameter details that do not exist.

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 states a specific verb ('List') and a precise resource ('currently authorized storage roots'), making the tool's purpose immediately clear. It also distinguishes itself from sibling file tools by emphasizing what it lists rather than operating on files or directories.

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?

The description provides clear context: it lists authorized storage roots, and explicitly notes that it does not require Accessibility or opening a file manager. This implies when to use this tool versus other file-related tools, though it does not explicitly name alternative tools or exclusion conditions.

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