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

Annotations cover only readOnlyHint and openWorldHint, so the description's disclosure of cost ($0.03 USDC per call over x402), the failed-calls-are-free guarantee, and the quote-then-sign payment flow adds genuinely useful context an agent cannot get from structured fields. It stops short of stating data freshness/latency or rate limits, so it is strong but not exhaustive.

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 purpose with clearly labeled sections ('When to use', 'Use instead', 'Parameters', 'Returns') that make it scannable. The only flaw is redundancy: the 'Returns' section restates the same list of outputs already itemized in the opening sentence, adding length without new information.

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 no-output-schema tool, the description covers purpose, scoping, the competing sibling, cost and payment mechanics, parameter requirements, and return shape. An agent has everything needed to decide to call it and to invoke it correctly, including how to handle the first unpaid call.

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 coverage is 100%, so baseline is 3, but the description adds real meaning the schema lacks: the schema declares zero required parameters, whereas the text clarifies 'ticker or cik (one is required)', resolving an either/or ambiguity. It also explains the purpose of the payment parameter (omit for a quote, sign and re-call).

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 opening states a specific verb and resource ('Run due diligence on a US public company in one call') and enumerates exactly what is computed (profile, revenue/profit growth, margins, leverage and cash ratios from SEC filings, key filings, 8-K summaries). It also names the sibling it is not: company_snapshot. An agent can distinguish it without opening any 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?

It gives an explicit when-to-use condition ('You are evaluating a US public company and want the analysis done') and a named alternative ('Use instead: company_snapshot for a quicker, cheaper overview'). The pricing/payment flow is also spelled out as a procedural step, leaving nothing to inference.

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