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

Annotations already cover safety (readOnly, idempotent, openWorld), so the bar is lower, and the description still adds valuable operational context: free official source, no key required, 5 independent NY Fed series, and a stated cost. Cost/source/auth details are genuinely beyond what the annotations provide.

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?

One long run-on sentence with marketing phrasing. The cost is stated redundantly ('$0.03 USDC x402 Base' then '[x402: 0.03 USDC per call on Base]'), and the parenthetical about news is filler rather than load-bearing detail.

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 and a trivial single optional param, the description adequately describes the return content (series, volumes, dispersion, spread) and the commercial/access terms. It is close to complete for such a low-complexity fetch tool, missing only any note on time range or refresh cadence.

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 100%, but the single 'input' parameter's description is just a truncated copy of the tool description, adding no real semantics. Per the high-coverage baseline, 3 is the ceiling absent extra parameter meaning.

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 names a very specific resource set (SOFR/EFFR/TGCR/BGCR/OBFR, volumes, percentile dispersion, SOFR-EFFR spread) that no sibling tool covers, so an agent can distinguish it from exchange_rates_verified or ecb_macro. It lacks an explicit verb like 'fetches' but the data it returns is unambiguous.

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?

It implies a use case ('The input for Fed/CPI prediction markets') and gestures at the timing value ('the funding-stress signal before it hits the news'), but never states when to prefer this over siblings like polymarket_markets or when it is not appropriate. Usage is inferable, not stated.

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