mouse_position

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false. The description goes further by disclosing the lock-lifecycle behavior: the VM remains locked by this session and the agent must call vm_unlock when finished. This is valuable context beyond what the annotations provide, though the phrasing is slightly ambiguous about whether the tool itself acquires the lock.

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 two concise sentences with no filler. The primary purpose is front-loaded, and the important lock/unlock caveat is included without repeating schema or annotation information.

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 one-parameter read-only tool, the description covers the operation and the essential lock cleanup requirement. The only notable omission is the return format for the mouse position (e.g., coordinate units or screen space), especially since no output schema exists, but this does not block 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?

Schema description coverage is 100%, and the schema already documents vm_name with a pattern and a clear description. The tool description adds no additional parameter-level detail, so the baseline of 3 is appropriate.

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 ('Read') and a precise resource ('current mouse pointer position'), making the tool's purpose immediately clear. It is also easily distinguished from sibling movement and click tools, which change state rather than read it.

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 read semantics clearly imply when to use this tool, and the second sentence adds a concrete operational context: the VM remains locked and vm_unlock must be called afterward. The main gap is that it does not explicitly contrast this tool with alternatives like mouse_move or qemu_mouse_move, but the intended usage is still evident.

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