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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds real behavioral context beyond that: it aggregates three upstream sources into one normalized response, and it is free ($0.000 USDC per call). It stops short of noting rate limits, caching, or refresh cadence, so it is strong but not maximally rich.

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-loaded with the scope in the first sentence, then structured as Use when / Not for / Returns / Example. The example response is verbose but it is the section that carries the most information in a zero-parameter tool, so every part earns its place.

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 compensates by enumerating all returned fields (sp500_price, treasury_yield_10y, btc_price_usd, gas_standard_gwei, timestamp) and providing a concrete example with source attribution. Nothing an agent needs to call or interpret this tool is missing.

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?

The tool takes zero parameters and the schema is an empty object, so there is nothing to disambiguate. This matches the baseline of 4 for a parameterless tool; the description correctly claims no input is needed.

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 scope: Fed rate, inflation proxy, S&P 500, BTC, ETH, and gas in a single normalized call. It explicitly distinguishes itself from siblings as 'the only tool that gives you macro + crypto in one shot,' so an agent can separate it from token_price or gas_tracker without opening a 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?

Provides explicit 'Use when' and 'Not for' blocks, and names the alternatives for the excluded cases (token_price, gas_tracker, funding_rates for single-asset depth; dune_query for history/time series). No inference is required to route correctly.

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