calculate_bom_cost

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

Annotations already declare this a safe, read-only, idempotent operation, so the safety burden is off the description. The description adds genuine domain behavior beyond the annotations: the Basic-vs-Extended library rule, the exact +¥20/type feeder surcharge, and that the tool proactively suggests cost optimizations. It still omits how results are produced (live JLCPCB lookup given openWorldHint=true) and the return shape.

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?

Two tight sentences with the core purpose front-loaded and no filler. Slightly dense in the second sentence but every clause carries information.

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 single-parameter, read-only calculator with no output schema, the description covers the cost model, fee tiers, and the advisory output adequately. It could still note whether external JLCPCB data is queried at call time, which would matter for latency and freshness.

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?

Only one parameter (queries) and schema description coverage is 100%, with examples for accepted forms ('STM32F103C8T6', 'SP3485', '0603 10k'). The description adds nothing about the parameter, so the high-coverage baseline of 3 is correct.

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?

States a specific verb and resource ('Calculate PCBA component cost breakdown') plus the additional scope of JLCPCB SMT surcharges, which distinguishes it from the generic calculate_fab_cost sibling. It does not explicitly name that sibling or contrast its scope, so it falls short of a 5.

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?

Usage is implied by the SMT/JLCPCB cost framing but never stated: there is no 'use this when you need X, not Y' and no mention of calculate_fab_cost, calculate_smt_feeder_matrix, or export_manufacturing_bom as alternatives. An agent can guess the context but must infer the boundary with sibling cost tools.

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