run_erc

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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the description is not obligated to restate those. It adds real value beyond them: the verdict vocabulary (PASS/WARN/FAIL/UNVERIFIED), the reason UNVERIFIED can occur (no report produced), that findings are keyed by stable ids and item UUIDs, and that execution shells out to kicad-cli independently of a running app.

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?

A single front-loaded sentence with the verb and scope first, the return contract second, and the environment note last. Dense but every clause carries information; the nested parenthetical slightly hampers scanability.

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?

An output schema exists, so return values need not be enumerated, yet the description still summarizes the verdict model. Combined with the whole-hierarchy scope and the runtime-dependency note, an agent has what it needs; only error/timeout behavior for the underlying kicad-cli invocation is unaddressed.

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?

Schema description coverage is 100%, including the severity enum's semantics, so the schema carries the parameter burden and a baseline of 3 applies. The description adds nothing about schematic_path or severity, but nothing is left ambiguous either.

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 (Run), a specific check (KiCad's Electrical Rules Check), and an explicit scope (the whole schematic hierarchy) via a named engine (kicad-cli). This cleanly separates it from the PCB-side sibling run_drc without requiring the schema to be opened.

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 tool's role - run it to validate a schematic's electrical rules - and the note that it "works whether or not KiCad is open" is a mild environmental condition. However, it never states when to prefer this over run_drc, review_schematic, or kicad_doctor, and no prerequisites are given.

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