pcb_place_pad

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

With no annotations, the description carries the full burden and does substantial work: it discloses validation behavior ('Any other word is refused; it used to become a round pad'), the SMD vs through-hole semantics, and that unit conversions are kept exact rather than rounded. It still omits prerequisites (must a board be active? does the net need to exist?) and whether the placement is undoable, but the disclosure goes well past the minimum.

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 action and the disambiguating scope lead, followed by use cases and then per-parameter notes, so a reader can stop early. The Args block is dense but every line adds information; the docstring framing is slightly verbose but not padded.

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 10-parameter mutation tool with no annotations this is nearly complete: purpose, use cases, parameter meanings, and validation quirks are all present, and an output schema exists so return values need not be described. The remaining gap is preconditions on the active document and net existence, which an agent would still have to discover.

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 0%, so the description must compensate entirely and it does: all ten parameters are explained with units, defaults, and meaning. It also supplies the shape vocabulary (including the long-form aliases the library tools accept) that the schema leaves as a bare string with no enum, and clarifies that units governs both position and every size.

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 ('Place a standalone pad on the active PCB') and immediately scopes it against the large family of pad-related siblings with 'Not part of any component.' An agent can distinguish this from lib_add_footprint_pad or pcb_place_via without opening any schema.

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?

Gives concrete use cases (fiducials, test points, mounting holes) and a decision rule for the key parameter branch (hole_size=0 for SMD, nonzero for through-hole). It does not name a specific alternative sibling for the 'I want a pad inside a footprint' case, so the routing is implied rather than explicit.

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