List PCB layers

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

Annotations already establish read-only/idempotent behavior, so the description adds value by disclosing prerequisites (correct .PcbDoc opened and focused) and error behavior (empty or partial data if no board focused). This goes beyond the structured data.

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 well organized into labeled sections (Purpose, When to use, Parameters, Returns, Prerequisites, Errors). Every sentence provides useful information without unnecessary fluff, making it highly concise and scannable.

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?

The description covers purpose, usage, parameters, return format, prerequisites, and error conditions. The return format is somewhat vague ('Bridge-specific JSON'), but for a simple listing tool this is adequate. It could mention the existence of get_pcb_layer_stackup to avoid ambiguity but otherwise is complete.

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 has zero parameters and schema coverage is 100%, so the baseline is 4. The description explicitly states 'Parameters: None,' which is redundant but consistent. No additional parameter semantics are needed.

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 the tool's specific verb and resource: 'List electrical and mechanical layer metadata for the active PCB.' It clearly distinguishes its scope (active PCB) and mentions concrete use cases like 'export layer names/ids,' which helps differentiate it from sibling tools like get_pcb_layer_stackup.

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?

There is an explicit 'When to use' section with clear scenarios ('Layer stack review, export layer names/ids'). While it does not explicitly name alternatives or exclusions, the context provided is sufficient for an agent to determine when this tool is appropriate.

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