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

Annotations give readOnlyHint and openWorldHint, but the description adds operational behavior they cannot express: the $0.006 USDC x402 cost, that failed calls are free, and the two-step quote-then-sign flow via the payment parameter. That is exactly the kind of billing/auth context an agent needs before invoking a paid tool.

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-loads the core purpose, then cleanly segments payment, when-to-use, alternatives, parameters and returns. Every sentence carries information; no filler or restatement of the name.

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 summarizing the return shape (profile, filings[] with links, key financials for two fiscal years plus the latest quarter). Combined with the payment flow and alternatives, an agent has everything needed to call it correctly.

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 the baseline is 3, but the description adds meaning the schema omits: it clarifies that ticker or cik is required (the schema declares zero required properties), documents the filings range 1-40 with default 8, and gives an example form type. Useful disambiguation beyond the field-level descriptions.

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 verb and resource ('Get a one-call snapshot of a US public company from SEC EDGAR') and enumerates exactly what the snapshot contains: profile, recent filings with links, and named financial metrics. It explicitly differentiates itself from siblings company_due_diligence, sec_company and sec_financials, so an agent can select it without opening other schemas.

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?

Contains explicit 'When to use' and 'Use instead' sections naming three alternatives with the exact conditions that select each (due diligence for growth/margins/leverage/8-Ks; sec_company or sec_financials for a single part, noted as cheaper). Nothing is left to inference.

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