API Tool Calls

EV Charger Installation Planner

ev_charger_install_cost

Read-onlyIdempotent

Work out the circuit a home EV charger needs, panel triage, utility install cost references and federal credit rules. Returns safety first, the exact 125% minimum breaker calculation, panel triage, unpriced extras and dated federal 30C rules. Reference cards are utility and DOE program figures, not a price for this home. A licensed electrician and permit are needed; confirm local requirements and inspection. Pure rules and Decimal, no network, model or clock. Web and MCP share the free daily allowance.

Example tool call

This call uses example arguments supplied in the tool’s input schema.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "level": "level2",
      "charger_amps": 48
    },
    "name": "ev_charger_install_cost"
  }
}

Input Schema

Name	Required	Description
`level`	No	Charging level; omit when unknown.
`extras`	No
`run_feet`	No	Estimated routed panel-to-charger length, not straight-line distance.
`panel_amps`	No	Panel/service rating, echoed only; a panel label alone cannot decide an upgrade or price the job.
`spare_space`	No	Compatible breaker space for a new circuit.
`charger_amps`	No	Rated or installer-set maximum charging current in amps.
`installed_on`	No	Placed-in-service date YYYY-MM-DD; omitted follows the after-2026-06-30 rule.
`capacity_check`	No	Electrician load calculation result; not_done means not assessed.
`existing_circuit`	No	Suitable dedicated circuit already at the parking spot.

Schema Changelog

Changes observed during successful MCP inspections.

AddedOct 4, 2026
RemovedOct 4, 2026
AddedOct 3, 2026

TDQS

A3.5/5.0

Behavior4/5

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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, but the description adds real context beyond them: reference cards are DOE/utility figures and not a price for this home, the tool is pure rules/Decimal with no network/model/clock, and web and MCP share a free daily allowance (rate-limit disclosure).

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

Conciseness4/5

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

Purpose is front-loaded in the first sentence and the following sentences carry distinct caveats (reference-figure disclaimer, licensing, determinism, rate limit). It is dense but each sentence contributes; no obvious filler.

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?

With no output schema, the description carries the burden of describing returns, and it does list them (safety first, breaker calc, panel triage, unpriced extras, 30C rules). Zero required parameters is not clarified, but otherwise it is complete enough to call correctly.

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 coverage is 89%, so the schema already documents nearly all nine parameters in detail. The description adds domain framing (125% minimum breaker calculation, panel triage, unpriced extras, dated 30C rules) but no parameter syntax beyond what the schema provides, so the baseline of 3 applies.

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

Purpose4/5

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

The description states a specific verb-and-resource set: work out the required circuit, panel triage, utility install cost references, and federal 30C credit rules for a home EV charger. It is clearly distinguished from generic cost siblings by its EV-charger scope, though it does not name any sibling it competes with.

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

Usage Guidelines2/5

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

There is no explicit when-to-use guidance or routing against alternatives among the many *_cost siblings. The only guidance is a caveat that a licensed electrician and permit are needed, which is a disclaimer rather than a usage condition.

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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