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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses the most decision-relevant behavior an agent needs: a $0.5 USDC per-call charge, the exact unpaid-call response (x402 payment requirements), and the three ways to supply payment (X-PAYMENT header, PAYMENT-SIGNATURE header, or params._meta). It does not describe failure modes after payment or result completeness/partial-failure behavior. Note a mild tension: the tool fetches live external sources (Wikidata, DNS, SEC) and moves funds, which sits awkwardly with openWorldHint=false and readOnlyHint=true, though the description does not make conflicting claims outright.

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 with the value proposition, then scope, then price and payment mechanics — a sensible ordering with little filler. The payment-recovery sentence is dense but each clause (header names, _meta path) carries operational information the agent needs to retry.

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 6-parameter tool with no output schema and only 50% schema coverage, the description does the heavy lifting by naming the result sections returned and the payment handshake. Remaining gaps are the meaning of `authorized`, the toggle defaults, and what a paid-but-partial result looks like.

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?

With only 50% schema description coverage, the description partially compensates: it explains that ticker drives SEC filings and groups the DNS, SEO and filings data into the bundle, implying what includeDns/includeSeo/includeFilings toggle. It never explains the required `authorized` boolean ('Must be true'), the punycode/ASCII domain format, or the defaults on the three include flags.

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 opens with a specific verb+resource ('One paid call for a full company profile') and enumerates the bundled data sources — homepage firmographics, Wikidata, DNS/email-domain diagnostics, on-page SEO, SEC filings. This implicitly distinguishes it from the single-purpose siblings (company_facts, company_filings, dns_records, seo_audit, email_domain_check), though it never names them 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?

Usage is conveyed indirectly: 'when a US ticker is known' scopes the filings portion, and 'Company-level facts only' excludes person-level lookups. However, there is no explicit statement of when to choose this bundle over the cheaper single-purpose sibling tools, nor any exclusion for domains that lack a homepage or ticker.

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