PCB layer stackup

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds useful context beyond annotations by specifying the return format ('JSON stackup structure from the bridge') and the prerequisite 'Active/focused PCB.'

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-structured with clear labels (Purpose, When to use, Parameters, Returns, Prerequisites), extremely concise, and front-loaded. Every sentence provides necessary information without 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?

The description covers all necessary context: purpose, usage conditions, return type, and prerequisites. Combined with rich annotations, it is fully sufficient for an agent to understand and invoke the tool correctly despite the absence of an output schema.

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 the input schema is empty. The description explicitly states 'Parameters: None,' which is consistent and provides baseline clarity. Per the scoring guide, 0 params earns a baseline of 4.

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 states the tool retrieves the physical stackup (dielectrics, thicknesses) for the active PCB, using a specific verb and resource. It distinguishes from sibling tools like get_pcb_layers and get_pcb_rules by focusing on the stackup details.

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 a clear 'When to use' section specifying impedance/SI questions tied to stackup. While it doesn't explicitly mention when not to use it or alternative tools, the context is sufficient for most agents to select it appropriately.

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