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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), yet the description goes further and discloses the cost ($0.02 USDC on Base), the x402 payment handshake, the free first call with no payment_header, and that the server never holds or spends a wallet. That is exactly the extra context annotations cannot express.

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 cost is front-loaded in a bracket tag and the routing rule comes before the payment mechanics. It is dense with no filler, though the closing payment sentences are slightly repetitive of both the schema and the opening tag.

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 paid read-only search with no output schema, the description supplies the complete picture an agent needs: what is searched, how to narrow it, when to prefer the sibling, and the full two-step payment procedure.

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%, including a fully spelled-out payment_header object, so the schema carries the parameter semantics. The description's payment-flow narrative (call with no header first, then resend with the signed header) largely restates what the schema already documents, so it adds little beyond the baseline.

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+resource (searches the actual TEXT of SEC filings) plus scope (since 2001, any company, by phrase) and even names the upstream index it uses. It explicitly contrasts itself with sibling edgar_filings, so an agent can disambiguate without opening either 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?

Gives an explicit routing rule: use this when you don't know which company filed, use edgar_filings once you do. That is a clear when-to-use / when-to-use-something-else statement naming the concrete alternative.

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