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

Annotations already cover the safety profile (readOnly, idempotent, openWorld), but the description adds non-obvious behavior: the call returns x402 payment requirements unless payment_signature is supplied, plus explicit pricing. That gating behavior is essential context an agent cannot infer from the schema and is genuinely additive.

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 primary action and scope, then usage, then payment mechanics. The '[Company & tax]' tag and 'Sample: /samples/sec-edgar' are mildly extraneous but the whole thing stays tight.

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?

No output schema and no required parameters, so the description must convey what comes back and how the payment handshake works — it does both (profile, filings, financials, payment requirements). It omits pagination/limit behavior and error handling, keeping it short of a 5.

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 all seven parameters (cik, name, ticker, forms, limit, financials, payment_signature) are already documented. The description adds only the payment_signature gating semantics, which matches what the schema says, so baseline 3 applies.

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+scope: 'Pull a US-listed company's official SEC profile, latest filings and headline financials.' This clearly separates it from generic siblings like lookup_company and counterparty_due_diligence by naming the primary source (SEC EDGAR) and the three payload types.

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?

'Use when you need primary-source data on an SEC registrant' gives a clear selection condition tied to data provenance. It stops short of naming an alternative sibling to route away from, so it is not a full 5.

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