lib_add_footprint_arc

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

With no annotations, the description carries the full burden and does disclose useful behavior: layer defaults and accepted values, footprint_name targeting behavior including refusal on failure, and exact unit handling. However, it does not state whether the change is saved immediately, what permissions or document state are required, or what happens on partial failure.

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 description is front-loaded with the core action and then structured as a compact argument list. Every sentence serves to explain a parameter or behavior, with no redundant prose.

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?

It covers all parameters and key behavioral quirks despite no annotations and no schema descriptions, and the output schema already documents the return shape. The main remaining gap is arc orientation/direction semantics for start and end angles, plus persistence or save-state expectations.

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%, and the description compensates by documenting every one of the nine parameters with units, defaults, and practical meaning. It adds particularly useful detail for layer, footprint_name, and units that the schema alone does not convey.

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?

The description states a specific verb and resource: adding an arc to the current footprint. It clearly distinguishes footprint arcs from symbol arcs via the resource name, but it does not explicitly contrast itself with siblings such as lib_add_symbol_arc or pcb_place_arc.

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?

There is no explicit guidance on when to use this tool versus alternatives, nor any stated preconditions for adding an arc. The footprint_name behavior is described, but that is parameter semantics rather than usage guidance.

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