Picodev Lab

Capture analog signals

capture_analog

Sample the voltage of 1 to 4 board pins (the board's own numbers: Nano A0-A7 = 14-21, Uno A0-A5 = 14-19, Mega A0-A15 = 54-69; by default the setup's scope probes) at rate_hz (100 to 10 000) for duration_ms (1 to 10 000 simulated ms), 200 000 samples at most in all. An ADC input reads the voltage the circuit applies; any other pin, its logic level times the supply (PWM shows as a square wave). Simulation only: refused during a turn on a real bench, whose analyser has no analog channel. Read the result with read_capture.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "capture_analog"
  }
}

Input Schema

Name	Required	Description	Default
`pins`	No
`rate_hz`	No
`session`	No
`agent_token`	No
`duration_ms`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed7 schema fields changedOct 23, 2026
- addedInput schema / properties / agent_token / anyOf
```
Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]
```
- addedInput schema / properties / agent_token / default
```
Added value: +null
```
- removedInput schema / properties / agent_token / type
```
Removed value: -"string"
```
- addedInput schema / properties / session / anyOf
```
Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]
```
- addedInput schema / properties / session / default
```
Added value: +null
```
- removedInput schema / properties / session / type
```
Removed value: -"string"
```
- removedInput schema / required
```
Removed value: -[
-  "session",
-  "agent_token"
-]
```
First observedOct 21, 2026

TDQS

A4.4/5.0

Behavior5/5

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

Beyond the minimal annotations, the description discloses key behavior: simulation-only refusal on a real bench, how ADC vs non-ADC pins are interpreted, PWM appearing as a square wave, the default scope-probe pins, and the 200,000-sample cap. These are substantive operational constraints an agent needs before invoking the tool.

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 front-loaded with the core action and key parameters, then adds behavioral and simulation constraints efficiently. Despite being a dense paragraph, every clause contributes hardware-specific or operational meaning.

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

Completeness4/5

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

For a 5-parameter capture tool with no output schema, the description provides enough to call it correctly and retrieve results via read_capture. However, it leaves session and agent_token unexplained and does not clarify what the capture result reference looks like.

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

Parameters3/5

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

Schema description coverage is 0%, so the description must carry parameter meaning. It does well for pins, rate_hz, and duration_ms with ranges and pin mappings, but it never explains session or agent_token, and it only partially covers defaults for rate and duration.

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 states a specific verb and resource: 'Sample the voltage of 1 to 4 board pins' at a given rate and duration. It clearly separates analog ADC readings from non-ADC pins whose logic level is sampled, and tells the agent to read the result with read_capture.

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?

It gives clear usage context by specifying analog voltage sampling, pin count, rate/duration ranges, and the simulation-only restriction. It also names read_capture as the follow-up tool, but it does not explicitly say to use capture_logic for digital captures, leaving that sibling relationship implicit.

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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