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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds that a source attribution and page URL are returned, which is useful, but it discloses nothing about the assumptions behind the estimate, unit conventions, or rounding, which matters for a savings calculator.

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?

It is short and front-loaded, leading with the resource and tariff. The 'Same code as <URL>' clause is promotional noise that does not help an agent invoke the tool, but the overall size is appropriate and not padded.

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?

With no output schema present, the description does at least note that an estimate plus source URL is returned, which is more than nothing. But for a six-parameter financial calculator it omits the meaning of the estimate, the tariff assumptions, and the undescribed hours_per_day parameter, leaving real gaps.

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 83%, so the schema documents count, led_cost, new_watts, old_watts, and other_kwh on its own. The description adds no parameter-level meaning and leaves hours_per_day (undescribed in the schema) unaddressed, so it is a baseline case where structured fields do the work.

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 the resource (Japan LED replacement savings) and adds tariff context (TEPCO Juryo Dento B, 30 A), so the domain is identifiable. However, it largely restates the title verbatim and never articulates the actual computation (cost/payback comparison between old and new wattage), so it stays at the vague-purpose tier rather than a specific verb+resource claim.

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?

There is no guidance on when to use this tool versus its obvious siblings kr_led_savings, ph_led_savings, and tw_led_savings. The only differentiator is the implicit 'Japan/TEPCO' framing; nothing tells the agent to pick this one for Japanese tariffs and a different sibling elsewhere.

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