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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description adds useful behavior beyond those: up to 4 years of annual data or 4 quarters of quarterly data, transpose orientation, TTM income-only restriction, and the Yahoo Finance/yfinance source with no API key. This is solid additional context, though edge cases like missing data or invalid symbols are not covered.

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 well-structured, scannable, and front-loaded with purpose and return shape before usage guidance, options, and source. Every sentence provides value, there is no filler, and the bullet format makes the when-to-use cases easy to parse.

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 read-only financial-data fetch tool, the description is largely complete: it states what data is returned, the available statement and frequency options, the output orientation, and the data source. Since an output schema exists, return-value details need not be in the description. It loses a point because it does not map the core inputs (especially symbol) explicitly or clarify which of the many unrelated-looking schema fields are meaningful, so an agent must infer some invocation details from the schema.

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 description provides literal options for statement ('income', 'cashflow', 'balance') and freq ('yearly', 'quarterly', 'trailing') and notes that trailing is income-only, which is genuinely useful. However, with schema description coverage reported as 0%, it only partially compensates: 'symbol' is implied but not described, and the many financial-platform parameters in the schema (wholesaler_ids, source_resource_id, additional_display_fields, etc.) are left unexplained, which could confuse an agent inspecting the params object.

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 opens with a specific verb and resource: 'Fetch income statement, cash flow statement, or balance sheet for a stock.' It names the three statement types explicitly, which makes the tool's purpose unambiguous and helps distinguish it from siblings like GetPriceHistory, GetDividendsAndSplits, or GetEarningsHistory.

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 includes a dedicated 'Use this tool when' section with concrete fundamental-analysis scenarios such as needing revenue, net income, EPS, operating margins, cash flow from operations, CapEx, and liquidity ratios. It gives clear context but does not explicitly name when-not-to-use conditions or alternative sibling tools, so it stops short of a 5.

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