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

Annotations only declare readOnlyHint=false, openWorldHint=true and idempotentHint=false; the description goes well beyond them, disclosing per-call USDC charging, wallet sourcing, budget caps, the confirm_over_cap guarantee that never raises session/daily budgets, out-of-US refusal behavior, and a third-party-data safety warning. This is unusually rich behavioral disclosure for a metered tool.

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?

Front-loads purpose, then the US-only constraint, then the paid/budget model, then a scannable product table. Dense but every line earns its place; the repeated '$0.005' pricing and a few clipped entries add minor noise.

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 does attempt return-value coverage (seven-day day/night periods, temperature/dewpoint/humidity/wind fields, forecaster reasoning in discussions). Completeness is slightly undermined by the truncated product entries, which leave some return details unfinished.

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% for the top-level object, but the nested params bag is additionalProperties:true with no per-product detail, so the description's per-product parameter lists (state*; lat, lon; wfo, gridX, gridY; etc.) carry real weight. It loses a point because several product entries are visibly truncated mid-sentence.

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 and resource (NWS forecasts, observations, alerts) and enumerates every product with its price and parameter set. An agent can tell it apart from siblings like free_sample and call_product without opening any schema.

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?

Explicitly routes the agent to free_sample before paying and states the US-only constraint (points outside the US are refused free of charge). It does not, however, contrast itself against the other product-calling siblings such as call_product or list_products.

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