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

With no annotations, the description carries the behavioral disclosure burden, and it does so well: it reveals that a bundled mock-location helper service is auto-installed on first call, that the mock fix is visible to every app using LocationManager/FusedLocationProviderClient, and that the isFromMockProvider flag cannot be hidden. This is meaningful beyond the schema. It doesn't mention whether previous location settings are restored or whether a subsequent clear call is needed, so it stops short of a 5.

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 front-loaded with the core purpose and packs useful behavioral caveats into three sentences. The licensing detail (Apache-2.0) is marginally extraneous but not distracting, and the overall length is justified by the need to explain the mock-provider limitation.

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 tool with no output schema and no annotations, the description covers the key operational context: supported API level, install-on-first-call behavior, scope of visibility, and an important app-level detection caveat. It could be strengthened by noting how to verify the mock location or how it interacts with device_clear_location, but it is sufficiently complete for safe 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?

Schema description coverage is 100%, so the input schema already documents all four parameters (udid, latitude, longitude, accuracy). The description adds no extra parameter-level meaning beyond what the schema provides, which is acceptable per the baseline for full schema 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?

The description states a specific verb and resource: "Mock GPS coordinates on an Android device for testing location-aware apps." This clearly distinguishes it from related siblings like device_get_location, device_clear_location, and ios_set_location by platform and operation, so an agent can route correctly without opening the 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?

The description provides clear usage context: it is for testing location-aware apps and requires API 26+. It also warns about apps that check Location.isFromMockProvider, which is relevant for deciding whether this tool is appropriate for a test scenario. However, it does not explicitly mention alternatives like device_clear_location or ios_set_location, nor state when not to use it.

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