design_list_circuit_blocks

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

No annotations exist, so the description carries the full burden and does: "Pure Python, no Altium" discloses that no host application or design state is touched, and the silent-ignore failure mode explains a non-obvious behavioral hazard in the paired write tool. Return shape is also described.

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 core action, then the rationale, then the return shape — a sensible order with little waste. The explicit "Returns:" block is mildly redundant given an output schema already exists, costing it a point.

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?

A zero-param discovery tool with an output schema needs very little, and this description still adds the workflow rationale and the silent-ignore trap. Nothing an agent needs before calling is missing.

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?

Zero input parameters, so the baseline is 4. The description does useful work by explaining what each returned block entry contains (required, optional, creates_nets) and that universal keys like sheet/lib_path/pins are already folded in, though these are output semantics rather than input params.

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?

Specific verb+resource ("list the canonical circuit blocks and their parameter contracts") with the scope of each returned entry enumerated. It also names the sibling it exists to support (design_add_circuit_block), so an agent can place it in the workflow without further inference.

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?

Explicitly prescribes when to call it: "Call this to author with the exact parameter names instead of guessing." It also gives the condition that makes this necessary rather than optional — a mistyped optional key is silently ignored — which is effectively a when-not-to-guess rule.

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