app_get_preferences

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

With no annotations, the description carries the full burden. It does disclose a genuine behavioral trait — values are null when no PCB or schematic is open — and "Get" implies a non-mutating read. It does not say whether values reflect live editor state or persisted document state, nor whether reading has side effects on the active document.

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 opening sentence and the null-value clause are front-loaded and earn their place. The trailing "Returns:" block restates the dictionary structure that the output schema already fully specifies, so it is largely redundant padding.

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 zero-parameter read with a full output schema, the description covers what is read, from where, and the degenerate no-document case. Nothing an agent needs in order to call it correctly is missing; the only shortfall is guidance on when this tool is the right choice among the many app_* siblings.

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 tool takes no parameters, so the baseline is 4; there is nothing to disambiguate. The description correctly does not invent parameter guidance, and the scope-selection condition (active board vs. active schematic) substitutes meaningfully for what would otherwise be a parameter.

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+resource ("Get ... preferences") and narrows the scope precisely: PCB snap grid/display unit from the active board, schematic visible/snap grid from the active schematic. An agent knows exactly what comes back. It does not, however, distinguish itself from near-siblings such as app_get_status or app_get_version.

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?

Usage is only implied: the null-value clause implies the tool is meant to be read while a board or schematic is open, which is a useful precondition. But there is no explicit when-to-use statement, no exclusion, and no pointer to an alternative (e.g., a setter counterpart or a status tool).

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