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

With no annotations, the description carries the full burden and does well: it discloses no payment/auth barrier, that data are passed through unchanged and may not be current, and enumerates the holiday-aware status values (fresh, PENDING, STALE, no publish, UNVERIFIED) that govern whether data is usable. It stops short of describing pagination or rate-limit behavior.

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?

The core purpose and the free/no-payment note are front-loaded effectively. However, three sentences of affiliation/endorsement boilerplate and the verbatim repetition of schema parameter constraints dilute the payload.

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?

There is no output schema, so the description must indicate return contents, and it does: each rate's source URL, terms notices, and a holiday-aware status. Combined with explicit date/rate parameter semantics, an agent has enough to call and interpret the tool, though return shape is only sketched.

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%, so the schema already documents all four parameters and their constraints. The description restates the same 'last (1-10) or startDate+endDate (YYYY-MM-DD, <=31 days, >=2018-04-02)' rules without adding meaning beyond the schema, so 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?

The description names a specific resource (NY Fed reference rates: SOFR, EFFR, OBFR, TGCR, BGCR) and its mode of delivery ('as published'). It is clearly distinguishable from most siblings by resource, though it does not explicitly name the near alternatives like market_quote or market_search.

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 signals 'FREE (no x402, no payment)' and 'market data only, not a forecast, not a recommendation,' which hints at routing versus x402_check and forecast-style tools. However, there is no explicit when-to-use statement or named alternative among the many market/tokenized-stock siblings.

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