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

Annotations only cover readOnlyHint and openWorldHint, and the description goes well beyond them: it discloses the data source (SEC XBRL API, public domain), provenance of each value (the form and filing date it came from), the exact payment model ($0.003 USDC via x402 on Base/Solana/Arc) and the failure policy (failed calls not charged). This is precisely the kind of behavioral context annotations cannot carry.

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 what the tool returns, then provenance, accepted identifiers, and pricing — logical ordering with almost no filler. The field enumeration is long but each item is substantive, so only minor tightening is possible.

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 an output schema present, the return shape need not be explained, and the annotations cover the safety profile. The description fills the remaining gaps — source, provenance, identifier forms, and cost/charging semantics — leaving nothing an agent needs in order to call it correctly.

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%, so the schema already documents company, years, and period, and the description's 'Ticker or CIK' merely restates the schema's own example. The 'per fiscal year or quarter' phrasing loosely maps to the period parameter but adds no format or syntax detail. Baseline 3 for a fully documented schema.

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 resource (key financial figures per fiscal year/quarter) drawn from SEC XBRL filings and enumerates the exact fields returned. An agent can tell this is a fundamentals-lookup tool rather than a filing-document tool. It does not, however, explicitly distinguish itself from siblings like sec_filings or sec_search, which a reader must infer.

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 implied — you call it to get tagged financial figures for a ticker/CIK — but there is no explicit when-to-use, when-not-to-use, or naming of the SEC sibling alternatives that would let an agent route confidently between sec_financials, sec_filings, sec_events, and sec_search.

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