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

Annotations already cover read-only, non-destructive, open-world semantics, so the description's real contribution is the cost model: USD 0.01 per call via x402/USDC on Base with failed calls not charged. That is exactly the kind of behavior an agent must weigh before invoking. It stops short of describing failure modes (e.g. invalid ticker) or latency/rate limits.

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?

Two sentences, purpose front-loaded, the returned-field list dense but each item carrying information (important since there is no output schema), and the cost caveat placed at the end where it reads as a warning. 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?

With no output schema, spelling out the returned financials and filing links is essential and done well; cost and non-charging on failure are also covered. The remaining gap is that required parameters are empty in the schema and the description never says whether ticker, CIK, or one-of is mandatory.

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 description coverage is 100% and the schema already explains both parameters, including that CIK is used 'instead of ticker'. The description's 'by ticker or CIK' restates that alternation without adding format or precedence rules. Baseline 3 applies since the schema does the work.

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 ('US public company profile from SEC EDGAR') and enumerates exactly which fields are returned, so an agent knows precisely what it will get. It implicitly distinguishes itself from company_search (lookup by ticker/CIK, not search) and company_lei (a full financial profile, not just an LEI), but never names those siblings explicitly.

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?

'by ticker or CIK' implies which inputs select this tool, and the pricing note hints it is a paid, deliberate call rather than a casual probe. However there is no explicit when-to-use versus company_search or company_lei, and no statement about what happens when both or neither identifier is supplied.

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