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

Annotations already establish the safe read profile (readOnlyHint=true, destructiveHint=false), and the description adds substantial context beyond that: data provenance (SEC Company Facts XBRL vs non-US issuer filings), latest-restated selection rule, exact-period-end semantics, discrete-quarter derivation with a 'Derived' marker, and which facts are out of scope.

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 core operation and resource, then layered with provenance, derivation rules, and exclusions. It is a dense paragraph rather than scannable sentences, but each clause carries distinct value (source, return set, quarter derivation, sibling routing) with no filler.

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 still describes the return set (standard line items such as revenue, net income, total assets, operating cash flow) and the exact-period/latest-restated semantics. Combined with provenance and explicit exclusions, it covers everything an agent needs to call and interpret the tool 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 all four parameters are already documented in the schema, including the 'FY'/'Q1'..'Q4' semantics and default behaviors. The description reinforces rather than extends the parameter details, so the baseline 3 is appropriate.

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 precise verb ('Get') and resource class ('company's income statement, balance sheet, or cash-flow statement') scoped to fiscal year and period. It explicitly distinguishes itself from siblings by naming GetRevenueBreakdown, GetFinancialFact, and CompareFinancialFact and describing what each covers instead, so an agent can route correctly without opening schemas.

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-not guidance: company-specific dimensional facts are excluded, and the description routes segment/geographic revenue to GetRevenueBreakdown and single-line-item/multi-period or cross-company lookups to GetFinancialFact or CompareFinancialFact. The 'FY for annual figures' hint further guides correct period selection.

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