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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and open-world behavior, so the safety profile is covered. The description adds genuinely useful context the annotations do not carry: it is free, requires no wallet or payment, and takes no arguments.

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 sentence, front-loaded with '[FREE]' and the preview intent. It is efficient, though 'No wallet, no payment' mildly restates the '[FREE]' / 'before paying' framing already established earlier.

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, but the description conveys that the return value is a representative sample of the paid tool's response. For a zero-argument, zero-cost preview that is sufficient; the only minor gap is not hinting at the fields the sample contains.

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 (empty object) already reflects that, so there is nothing to document. The description confirms 'no arguments needed', which matches the schema and removes any doubt about required input.

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 the exact resource (SEC EDGAR XBRL company facts, via edgar_company_facts) and states precisely what this tool returns: a free sample response showing the shape. It clearly distinguishes itself from the paid sibling it previews.

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 gives a clear condition for use: run this before paying 0.02 USDC to inspect the response shape. It stops short of an explicit 'use edgar_company_facts when you need real data' sentence, but the alternative and its rationale are strongly implied.

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