pcb_three_way_cross_reference

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

No annotations are provided, so the description carries the full burden. It discloses non-mutating behavior through verbs 'Compare' and 'Detects', and specifies exactly what is detected (DNP flag inconsistencies, MPN divergence, etc.). Mentioning 'Severity-graded per the playbook' gives insight into output structure, though it does not explicitly state read-only or dependency on prior parsing steps.

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 two sentences, front-loaded with the primary purpose. It packs a list of specific detection categories without unnecessary words. Every sentence earns its place, making it compact and well-structured.

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 tool has one parameter, no output schema, and no annotations. The description explains its core function and what it detects, but it omits important context such as prerequisites (e.g., whether schematic/BOM/layout must be parsed first) and the exact return format. 'Per the playbook' is vague, and without an output schema, the agent might be uncertain about how to use the results. This is adequate but has clear gaps.

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 has only one parameter (session_id) with 100% description coverage ('Session id.'). The tool description does not add any additional meaning to this parameter, so the baseline of 3 is appropriate. It does not explain how session_id is used in the context of this cross-reference.

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 defines the resource ('schematic, BOM, and layout component lists') in one pass. It lists concrete detection capabilities (missing components, footprint mismatches, etc.), which distinguishes it from the sibling pcb_cross_reference_schematic by emphasizing the three-way comparison.

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 gives no explicit guidance on when to use this vs alternatives. It implies use when you have all three component lists, but does not mention prerequisites (e.g., needing parsed data from pcb_parse_schematic/pcb_parse_bom/pcb_parse_layout) or exclusions. The sibling pcb_cross_reference_schematic likely covers a two-way comparison, but no differentiation is provided.

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