pcb_calc_pdn_impedance

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

With no annotations provided, the description carries the full burden and handles it well. It discloses the modeling approach (parallel RLC networks), the sweep behavior (freq_start to freq_stop), and the flagging criterion (target impedance formula). This gives the agent a solid mental model of how the tool operates, though it does not mention output format or side effects.

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 three concise sentences with no filler. The first sentence front-loads the primary purpose, and the following sentences add necessary technical detail without redundancy. Every sentence earns its place.

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?

Given the tool's complexity (12 parameters, no output schema, no annotations), the description covers the core model, sweep mechanics, and the key impedance target formula. It does not explain return values or clarify differences from similar PDN/decoupling tools, but the provided information is sufficient for an agent to understand the tool's role and basic invocation. It falls short of full completeness due to these omissions.

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%, so the baseline is 3. The description adds value by explaining how parameters map to the model (e.g., plane capacitance relates to plane_area_mm2, dielectric_constant, dielectric_height_mm) and by defining Z_target = V * ripple% / I_max, which semantically links supply_voltage_v, ripple_percent, and max_current_a. This extra context justifies a score above baseline.

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+resource: 'Frequency-swept PDN impedance profiling.' It elaborates with modeling details (VRM, bulk caps, MLCC decaps, plane capacitance as parallel RLC networks) and the specific action of flagging anti-resonance peaks exceeding a calculated target impedance. This clearly distinguishes it from broader PDN analysis tools like pcb_analyze_pdn or pcb_analyze_decoupling.

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?

The description implies usage for frequency-swept PDN impedance analysis and anti-resonance checking, but it does not explicitly state when to use this tool over alternatives or provide exclusions. No sibling tool is mentioned as a substitute, leaving the agent to infer the appropriate context from the technical wording alone.

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