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

Annotations already declare readOnly/idempotent/non-destructive, yet the description adds real substance: the feeder-fee economics, the matching precedence (LCSC number, then MPN, then value+chip size for passives), and the footprint-resize suggestion behaviour. "Free, read-only" partly restates the annotations and no limits or failure handling are mentioned, so not a 5.

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?

Roughly four dense sentences, front-loaded with the purpose and then the fee rationale, matching rules, and returns. No filler, though "Free, read-only" is largely redundant with the annotations.

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?

There is no output schema, but the description states what comes back (per-line status, part, price, total feeder fees). Combined with the fully documented single input, an agent has everything needed to call and interpret this tool.

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?

With one parameter and 100% schema description coverage, the baseline is 3. The description adds meaning the schema lacks: which fields actually drive matching (lcsc, mpn, and value + footprint for R/C/L), which tells the agent how to populate each BOM line.

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?

"Checks each BOM line against JLCPCB's basic and preferred-extended parts in stock" gives a concrete verb, resource and scope. The sibling names (check_project, estimate_build, request_*) are clearly different operations, so an agent can route here without ambiguity.

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 conveys the decision context: use this to find out which lines incur feeder fees before committing to Economic assembly. It does not explicitly name alternatives or state when not to use it, but for a single-purpose pre-check tool the trigger is clear.

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