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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), yet the description adds substantial context beyond them: the return shape, the authoritative-vs-best-effort distinction, OEM/Android-version variance, and the explicit warning that 'none' means unknown rather than 'no location'. This is exactly the kind of ambiguity an agent needs surfaced.

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?

Purpose is front-loaded, followed by return semantics and the highest-value caveat about 'none'. It is dense and slightly long, but every clause addresses a real ambiguity in interpreting the result rather than padding.

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 takes on the burden of explaining the return value and does so fully, including per-source meaning and null handling. Nothing needed to call or interpret the tool 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 description coverage is 100% with a single well-documented udid parameter, so the schema carries parameter meaning. The description adds no syntax or format detail beyond it, which is the correct baseline for full coverage.

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 and resource ('Read the Android device's current GPS location') and immediately situates itself relative to siblings by naming ios_get_location as its counterpart. An agent can distinguish it from device_set_location and device_clear_location without opening any 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?

Names the iOS counterpart and ties the 'mock' source to device_set_location, giving clear routing context. It stops short of explicit when-not-to-use guidance, but the sibling relationships it establishes are enough to select the right tool.

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