list_pcb_layers

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

Annotations already declare this as read-only, idempotent, and non-destructive. The description adds useful context beyond those annotations: the actual layer set is board-dependent and layer names may be renamed. This contextualizes the tool's behavior without contradicting the annotations.

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: two functional sentences plus a clear Args line. Every sentence contributes either purpose, usage guidance, or parameter meaning with no filler or redundancy.

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 simple one-parameter read-only tool with a corresponding output schema and strong annotations, the description is fully sufficient. It covers purpose, behavior variability, prerequisite usage, and parameter semantics, leaving no material gap.

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 schema only provides a default string for pcb_path, but the description fully explains the parameter semantics: it is a path to a .kicad_pcb file, optional, and can be omitted to use the configured default. This adds meaning well beyond the bare 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?

The description clearly starts with 'List all layers defined in the PCB stackup' and enumerates the layer categories, making the resource and action unambiguous. It also distinguishes itself from sibling list tools such as list_pcb_traces and list_pcb_nets by targeting the stackup layer set.

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?

Explicitly instructs the agent to call this tool before any tool that takes a layer name, and justifies this with per-board valid sets and common layer renames. This gives concrete when-to-use guidance and explains the dependency relationship.

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