design_add_part

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

With no annotations present, the description carries the burden well: it discloses that pins mapping to the same net merge automatically, that a net is created if absent and existing nets keep their power/ground flags, and that ok is False on duplicate refdes / empty connections / schema error. It never says whether plan_json is mutated in place or only returned in the response, which is a meaningful gap for a state-changing call.

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?

Front-loaded with the one-line purpose, then scope, then chaining, then args and returns. Every paragraph earns its place, though the docstring-style 'Args:'/'Returns:' scaffolding and reST double-backticks are slightly heavier than needed for an agent-facing description.

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 15-parameter, nested-object, no-annotation mutation tool this covers what an agent needs: what it does, how it composes with siblings, the connection-map semantics, the failure conditions, and the return shape. The output schema exists and the description still names the keys and the ok=False causes, which is the right level of redundancy.

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 coverage is 0%, so the description must compensate, and it does: all 15 parameters are addressed, with special attention on the non-obvious ones (connections as a pin->net map, power_nets/ground_nets only flagging nets created by this call, net_roles scoped to nets created here). The bundled 'value / footprint / lib_path / sheet / manufacturer / mpn / datasheet_url / role' sentence merely labels eight fields as 'standard Part fields' without explaining any of them, which is the main shortfall.

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+resource+scope: 'Add one part and wire its pins to named nets, in one call.' It explicitly positions itself as 'the atomic authoring primitive under the block/bus tools', which separates it from design_add_circuit_block and design_connect_bus, both named in the text.

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 clear usage context ('place a single arbitrary part -- an MCU, a connector, a regulator') and explicitly names the two recurring alternatives it chains with, plus the 'naming-agnostic' constraint that the caller must supply inventory-chosen names. It stops short of stating when NOT to use it in favor of the block/bus tools, but the chaining guidance makes the division of labor clear.

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