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

With no annotations, the description carries the full burden and does disclose the critical non-obvious trait: the tool is paid per call via x402 (USDC on Base), and payment_signature omission returns payment requirements per the schema. It does not state that it is read-only, nor does it cover rate limits or error behavior, but the payment disclosure is the highest-value behavioral fact here.

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?

The lookup scope, return contents, usage trigger, and payment note are front-loaded in that order. There is minor redundancy — 'Official SEC data' and 'straight from SEC EDGAR' say the same thing twice — but otherwise every sentence is load-bearing.

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 the returned fields (CIK, SIC, state, addresses, LEI, former names; revenue, net income, assets, liabilities, equity, cash, shares). Combined with the payment explanation, an agent has enough to call and interpret the tool, though pagination/error behavior is unspecified.

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 every parameter including payment_signature, forms, limit, and financials is already documented. The description restates the lookup keys and the forms filter but adds no syntax or format details beyond the schema (e.g., how forms is delimited is better shown by example).

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 first sentence gives a specific verb (lookup) and resource (SEC EDGAR company data) and enumerates the three deliverable groups: profile, filings, and XBRL financials. An agent can tell exactly what it gets back without opening the 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 explicitly states when to use it ('Use when you need a US-listed or SEC-registered company's official profile, latest filings... and headline financials'), which is a clear positive trigger. There are no sibling tools, so no alternative routing is needed, but it also gives no when-not-to-use guidance.

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