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

Annotations already declare readOnlyHint and openWorldHint, so the description doesn't need to restate safety; it instead adds genuinely new behavior: per-call cost of $0.002 USDC, accepted payment networks (Base, Solana, Arc), and that failed calls are not charged. That payment/auth detail is exactly the kind of context annotations cannot convey. Return window (latest + up to 24 months) is also disclosed.

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?

Three sentences, front-loaded with the identification and immediately followed by the exclusion clause and the cost. The aside 'the route name is kept for the owner' is mildly internal-facing meta-commentary, but it is short and clarifies the naming oddity in the tool name itself.

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?

For a single-parameter price lookup with an output schema, the description covers source, unit, history depth, exclusions, and payment model. Nothing an agent needs to call it correctly is missing, and return-value shape is rightly left to the output schema.

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% and the single 'months' parameter already documents the 1-24 range and default of 3. The description's 'up to 24 months of history' merely restates that bound rather than adding format, rounding, or lag semantics (e.g., whether the latest month is partial). Baseline 3 applies.

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 resource and unit (monthly uranium reference price, USD/lb U3O8), names the exact source series (World Bank PURANUSDM via FRED), and explicitly rules out competing benchmarks (UxC, TradeTech spot/long-term). An agent can distinguish it from price siblings such as energy_precious_metals_spot_fix or energy_thermal_coal_newcastle 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?

The 'Not the UxC or TradeTech spot or long-term quotes' clause tells the agent when this tool is the wrong choice and steers it to other uranium quote sources. It gives clear selection context but no positive when-to-use scenario (e.g., settlement vs. mark-to-market) and no prerequisites beyond the payment note.

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