One autonomous step

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

With no annotations, the description carries the full burden, and it does disclose the observe-decide-execute cycle plus what is returned ('the decision and execution result'). It does not say that the executed action is a real GUI mutation that may be irreversible, nor does it mention permission, session, or target-state requirements.

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?

Three short sentences, front-loaded with the core cycle and then the return value and intended usage. No filler, though the third sentence is a soft nudge rather than hard 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 4-parameter tool with a nested target object, no annotations, and no output schema, the description covers the return shape ('decision and execution result') but omits safety/permission context and says nothing about the target or goal parameters. Adequate but with clear gaps.

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 only 50% (goal and language are undocumented, and the nested target object carries most of the documentation burden), so the description needs to compensate and does not. It adds no meaning about goal semantics, language, or how target selection affects behavior; the only hint at dryRun is the word 'execute' in the summary sentence.

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 concrete verb chain ('Observe + let the vision GUI expert decide the next action + execute it'), which pins down the resource and scope as a single autonomous GUI step. The title 'One autonomous step' reinforces this and implicitly contrasts with whole-task siblings like computer_execute_task, though no sibling is named explicitly.

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?

'Useful for building your own loop in the calling agent' implies the usage context — the caller wants step-level control rather than a full autonomous run. However, it never states when NOT to use it or names the alternative (e.g. computer_execute_task or computer_action) that handles those cases, leaving the routing decision to inference.

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