umouse_get_capabilities

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

With no annotations, the description carries the behavioral burden well: it describes per-device return data, capability sources, connection generation, online status, and hidden tools. It also discloses execution-layer rejection for unknown capabilities and the UMSDK_TEST_CAPS test mechanism, though it does not explicitly state side-effect or permission details.

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 a single front-loaded sentence with dense but relevant information. Parenthetical details about capability sources and test capabilities earn their place, though the paragraph could be more scannable if split into shorter statements.

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?

Because there is no output schema, the description usefully names the per-device return fields and the hidden-tool reasons. It is nearly complete for a capability-query tool, with only minor gaps around result ordering or pagination that are unlikely to affect 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?

There is only one parameter, device_id, and the schema description coverage is 100%. The schema already documents omission behavior, multi-device requirements, and temporary IDs, so the description adds no additional parameter semantics beyond the schema.

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: querying device capabilities (voice / mouse_control / keyboard_control) and current executable state, including hidden tools and reasons. The purpose is clear, but it does not explicitly distinguish this tool from siblings such as umouse_status or umouse_list_devices.

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 implies when this is useful by explaining that unknown capabilities are rejected and that injection tools only work on devices declared supported. However, it never explicitly says when to call this versus alternatives like umouse_status or umouse_list_devices.

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