calc.engineer

op amp gain

op_amp_gain

Calculate voltage gain and output for operational amplifier circuits in inverting, non-inverting, and differential configurations. For inverting: Av = -Rf/Ri with input impedance equal to Ri. For non-inverting: Av = 1 + Rf/Rg with very high input impedance. For differential: Av = Rf/Ri applied to (V1 - V2). Reports gain in linear and dB, output voltage when input is provided, input impedance, and phase inversion status. Ideal op-amp assumptions (infinite open-loop gain, zero input bias current). Chain from ohms_law for power budgeting or resistor_color_code for component selection.

Input Schema

TableJSON Schema

Name	Required	Description
`vin_v`	No	Input voltage in volts (optional). When provided, computes actual output voltage. For differential topology, this is V1 (non-inverting input).
`rf_ohm`	Yes	Feedback resistor Rf in ohms. Sets gain magnitude in all topologies.
`ri_ohm`	Yes	Input/gain resistor in ohms. For inverting: input resistor Ri. For non-inverting: ground resistor Rg. For differential: input resistor on both channels.
`vin2_v`	No	Second input voltage in volts (differential topology only). This is V2 (inverting input).
`topology`	Yes	Op-amp circuit topology. 'inverting' uses Rf/Ri feedback with input to inverting terminal. 'non_inverting' applies input to non-inverting terminal with Rf/Rg feedback. 'differential' amplifies the voltage difference between two inputs.

Output Schema

TableJSON Schema

Name	Required	Description
`gain`	Yes	Voltage gain (Av). Negative for inverting topology.
`rf_ohm`	Yes	Feedback resistor value used in ohms.
`ri_ohm`	Yes	Input/gain resistor value used in ohms.
`vout_v`	Yes	Output voltage in volts (null if no input voltage provided).
`gain_db`	Yes	Gain in decibels: 20 * log10(\|Av\|).
`gain_abs`	Yes	Absolute value of voltage gain.
`topology`	Yes	Op-amp topology used.
`phase_inversion`	Yes	True if the output is phase-inverted relative to the input.
`input_impedance_ohm`	Yes	Input impedance in ohms. Inverting: Ri. Non-inverting: very high (returned as 1e12). Differential: Ri.

TDQS

A4.8/5.0

Behavior5/5

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

With no annotations, the description fully discloses behavior: it lists output items (gain in linear/dB, output voltage, input impedance, phase inversion), details formulas per topology, and states ideal op-amp assumptions. This gives the agent a complete understanding of the tool's results and limitations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is concise and well-structured: it starts with the core purpose, gives formulas for each topology, lists computed outputs, notes assumptions, and ends with chaining suggestions. No superfluous words; every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity (5 parameters, 3 topologies, multiple outputs) and that an output schema exists (though not shown), the description covers all essential aspects: formulas, outputs, assumptions, and usage context. It is complete for an agent to correctly invoke the tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema already has descriptive parameter descriptions (100% coverage). The tool description adds further value by explaining how parameters like ri_ohm are interpreted differently across topologies (e.g., inverting: input resistor, non-inverting: ground resistor). This enriches the agent's understanding beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool calculates voltage gain and output for op-amp circuits, specifying three topologies (inverting, non-inverting, differential). It distinguishes itself from sibling tools, which are diverse engineering calculators, by being the dedicated op-amp gain calculator.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides guidance on chaining with related tools (ohms_law, resistor_color_code) for power budgeting and component selection. It also notes ideal op-amp assumptions, implying limitations in non-ideal scenarios. However, it does not explicitly state when not to use this tool (e.g., for non-ideal or complex op-amp models).

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

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TDQS

A3.9/5.0

Disambiguation4/5

Despite 89 tools, each has a clearly distinct purpose with detailed descriptions that often reference related tools. Overlap exists (e.g., multiple LoRa/RF tools), but the descriptions are sufficient to distinguish them. Some confusion possible among similar-sounding tools like attenuator_pi and attenuator_tee, but the descriptions explicitly compare them.

Naming Consistency4/5

Consistent underscore-separated lowercase naming. Most tools follow a verb_noun pattern (e.g., capacitor_charge, wire_gauge) or noun_noun (power_cost). Minor inconsistencies such as 'bmi_calculator' vs 'solar_sizing' but overall predictable.

Tool Count2/5

89 tools is far too many for a single MCP server. This scope is more appropriate for multiple specialized servers. The sheer number will slow agent selection and increase cognitive load, reducing coherence.

Completeness3/5

Covers many domains (RF, solar, PCB, networking, math, etc.) but lacks depth in some areas (e.g., no three-phase power, no airflow calculations). Some domains have comprehensive coverage (LoRa/Meshtastic), but others feel incomplete for the tool count.

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