signalgrid_screen_lock

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

Annotations already declare read-only and non-destructive safety, but the description adds significant behavioral context: it composes three facts, uses a fail-safe logic, returns `null` when confirmation is impossible, and explicitly states 'unknown is never graded as locking.' This goes beyond what annotations provide and gives the agent a deep understanding of the tool's behavior.

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 compact and well-structured, front-loading the core purpose and then elaborating on the verdict logic and return fields. It uses several short sentences that each add value, but it is longer than strictly necessary for a one-parameter tool. The structure is clear, with section labels like 'Returns:'.

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?

There is no output schema, so the description correctly takes on the burden of explaining return values. It lists all dict keys (`locks_when_idle`, `password_on_wake`, etc.), explains the `null` edge case, and provides enough context about the composed facts to make the tool's behavior fully understandable without ambiguity.

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?

The single parameter `response_format` is fully documented in the input schema with enum and default, but the description does not mention it at all. With 0% coverage, the description fails to compensate or add any semantic meaning beyond the schema. However, the parameter is trivial and the schema suffices, so the minimum viable score 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 opens with 'Screen-lock / auto-lock hygiene: does this Mac lock itself when left idle?' which clearly identifies the tool's purpose and resource. It also explains the fail-safe `locks_when_idle` verdict, distinguishing it from sibling info-gathering tools like `signalgrid_installed_apps` and `signalgrid_os_info`.

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 context for when to use the tool: 'The walk-up risk on a shared or plant-floor device.' It also mentions 'Read-only; no elevation,' which helps the agent understand it's safe for assessment. However, it does not explicitly name alternative tools or when not to use it, so it falls short of a 5.

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