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

Annotations already establish read-only and idempotent behavior. The description goes further, explaining tag-fallback logic for ASC 606, classification by actual duration rather than fiscal-period labels, and returning null instead of fabricated zeros. No contradiction with annotations.

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 long but well-structured, starting with the core purpose, then return details, technical nuances, and usage guidance. The extra length is justified by the complexity of XBRL handling and a concrete return example, though it is not as concise as simpler tool descriptions.

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 no output schema, the description provides a detailed structuredContent example covering all concepts and period objects, plus behavior for missing concepts. Combined with strong annotations and a single-parameter schema, the agent has everything needed to invoke the tool and interpret results.

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?

The input schema already provides a full description of the ticker parameter with examples of both ticker and CIK formats, and the description merely restates this. With 100% schema coverage, the baseline of 3 applies; the description adds no new semantic detail.

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 clearly states it returns key financials from SEC XBRL company facts, listing specific metrics (revenue, net income, EPS, etc.). It distinguishes itself from sibling SEC tools by focusing on financial figures versus filings, holdings, or insider transactions.

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?

Explicit 'When to use' and 'When NOT to use' sections provide clear guidance for valuation/screening and exclusions like segment detail or analyst estimates. This gives the agent actionable direction for selecting this tool against alternatives.

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