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

Annotations already cover read-only and open-world behavior, and the description adds real value beyond that: the price ($0.002 USDC per successful call), the payment rail (x402 on Base, Solana or Arc) and the fact that failed calls are not charged. That is exactly the kind of billing context annotations cannot express.

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?

Two tight sentences: identity plus source first, then the disambiguation, then pricing. The clause about the route name being kept for the owner is slightly extraneous but explains why the tool name is misleading.

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?

Source, series ID, frequency, unit type, scope exclusion and cost model are all present, and an output schema exists so return values need no explanation. Minor gaps remain on index base/revision behavior, but nothing blocks correct invocation.

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?

Only one optional parameter (months) with 100% schema description coverage including the 1-24 range and default of 3. The description adds nothing about the parameter, but the schema fully carries it, so the 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?

Names the exact resource (US producer price index for steel mill products, BLS series WPU1017 via FRED) and the frequency/units (monthly index value). It explicitly disclaims being hot-rolled coil or rebar futures or spot benchmarks, which is the main confusion risk against siblings like energy_iron_ore_62_percent_fe or energy_thermal_coal_newcastle.

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?

Gives a clear use/not-use split: use it for the steel mill products PPI, not for HRC/rebar futures or spot benchmarks. It doesn't name a specific sibling to use instead for futures pricing, so the routing is only implied, not explicit.

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