pcb_compare_designs

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

With no annotations, the description carries the full burden of behavioral disclosure. It explains what the tool does (finds differences in listed categories), but does not explicitly state whether it is read-only or any side effects, nor does it mention error behavior or prerequisites. This is acceptable but lacks full transparency.

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 a single, well-structured sentence that front-loads the core action and lists specific comparison categories. Every word contributes to understanding the tool's purpose 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 the main functionality and parameter context sufficiently for a comparison tool with simple inputs. However, since there is no output schema, it could have clarified the return format or any prerequisites (e.g., sessions must be parsed), but the absence is not critical for this simple use case.

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 input schema already provides complete descriptions for both parameters (session_id_a as 'before' and session_id_b as 'after'), so the description adds little beyond restating the comparison scope. The baseline of 3 is appropriate since schema coverage is 100% and 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 uses a specific verb ('Compare') and clearly identifies the resource ('two design revisions') and the specific comparison dimensions (board size, layer count, components, nets). This distinguishes it from sibling tools like pcb_compare_simulation, which compare simulations rather than designs.

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 clearly conveys when to use the tool: when you need to compare design revisions and identify specific types of differences. It provides context but does not explicitly exclude alternatives or mention when not to use it, which prevents a 5.

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