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

Annotations already declare readOnly, idempotent, non-destructive and open-world. The description adds genuinely useful context beyond them: the response is a canned sample, it is free, and no wallet or payment is involved — important to prevent an agent from mistaking sample data for live data.

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?

A single sentence with the key qualifier '[FREE]' and the purpose front-loaded. Every clause earns its place; no filler.

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 zero-argument preview with a complete schema and no output schema, the description covers the essentials: what it returns (a sample shape), that it is free, and that no args are required. It stops short of describing what fields the snapshot contains, but for a preview tool this is acceptable.

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, so the baseline is 4. The description explicitly confirms 'no arguments needed', which aligns with the empty schema rather than contradicting it.

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 states a specific resource (a sample response for treasury_fiscal_snapshot) and its purpose (see the response shape before paying). It clearly distinguishes itself from the paid sibling treasury_fiscal_snapshot by naming it directly.

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 states when to use it — before paying 0.005 USDC, to inspect the shape — and notes no wallet/payment/arguments are required. It does not explicitly say to switch to the paid tool for real data, but that is strongly implied by 'before paying'.

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