As-reported fundamentals for a US public company from SEC XB

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

The description discloses the paid nature up front ('Paid (price from the live 402 quote)') and the payment mechanism via the optional payment_signature parameter, noting 'nothing is charged without it.' It also adds a disclaimer ('not investment advice') and describes output characteristics ('values are as filed, with sources and an evidence hash'). This goes beyond the sparse annotations (readOnlyHint: false, openWorldHint: true) and clarifies the financial side effect.

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 description is compact and efficiently structured: it leads with the paid warning, states the purpose and data fields, gives a usage hint, specifies input requirement, and ends with output provenance and a disclaimer. Every sentence earns its place, with no filler or redundancy.

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 tool with three parameters and no output schema, the description covers the essential call requirements: how to identify the company (ticker or cik), payment behavior, and the nature of the response (as-reported values, sources, evidence hash). It does not detail output structure, but for a 'quick fundamentals' tool this level is sufficient. The disclaimer also addresses a potential misuse.

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 the baseline is 3. The description adds a clarifying note that either ticker or cik is required, but this is largely redundant with the per-parameter descriptions ('Provide this or ticker' / 'Provide this or cik'). It does not add meaningful semantics beyond what the schema already provides.

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 names a specific resource (SEC XBRL filings), a clear action (as-reported fundamentals), and the exact data fields (revenue, net income, assets, cash, EPS). It is easily distinguished from sibling tools, none of which target SEC financial data, and the use case 'quick fundamentals without a data vendor' adds specificity.

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?

The description gives a clear usage context: 'Use for quick fundamentals without a data vendor' and explicitly states the input requirement: 'Give either ticker or cik (one is required).' It does not name alternative tools or exclusion conditions, but the context is sufficient for an agent to decide when to use it.

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