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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that: it is always paid ($0.50 per calculation in USDC via x402, no free allowance, per-item billing for up to 50), uses a stored table with no outside call, and enumerates the four verdict values. That is genuinely useful behavioral context.

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?

Purpose is front-loaded, but the description is one sprawling run-on sentence with stacked parentheticals (data source, GeoNames, pricing) that makes it harder to parse than necessary. Every element is relevant, yet the structure could be broken into discrete sentences without losing content.

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, the description still discloses the verdict vocabulary, the data source, the resolution behavior for coordinates, and the payment model, which is sufficient to call it correctly. It omits what happens for an unknown place or how 'unknown' verdicts arise, a minor gap for a read-only computation tool.

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 coverage is 100%, so the baseline would be 3, but the description adds meaning the schema lacks: the input object shape {place, month}, place as a GeoNames id or a "lat, lon" string resolved to the nearest table place with distance, month bounded 1-12, and how sentence/spec/design/items substitute for each other. It adds genuine constraints beyond the schema's passthrough objects.

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?

States a specific verb+resource: computes long-term mean daily minimum and mean temperature for a place in a month from NASA POWER, compares it to the design's minimum laying temperature, and returns a verdict. It names the data sources and even distinguishes itself from design_cable, which it consumes as input, so an agent can separate it from siblings.

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?

Implies the usage condition clearly (checking a site/month against the cable's laying limit) and explains the three input modes: sentence, spec/design from design_cable, or a batch list. It does not explicitly contrast with alternatives such as burial_depth or check_cable, so it stops short of full when/when-not guidance.

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