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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so safety is covered. The description adds substantial behavioral context: the 28-credit cost debited even when the filing is missing, has no cash flow statement, or is not an SEC filing; the 404 response for missing statements; the light_weight_mode payload reduction; and the SEC-only availability. 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 dense but front-loaded with the core purpose, and every substantive sentence earns its place: purpose, identification, relationship to get_filing_statement, error behavior, cost, light mode, and jurisdiction. It is slightly long, and the trailing 'POST /api/v1/data/cash-flow-statement; FINANCIAL_API_DOCUMENTATION.md' is somewhat redundant with the schema/title, but the overall structure is efficient.

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, idempotent fetch tool with 6 optional parameters and no output schema, the description is complete: it covers identification modes, required-versus-optional combinations, error semantics (404), cost implications, jurisdiction restrictions, and a payload-lean option. An agent has everything needed to invoke it correctly without additional documentation.

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 each parameter. The description adds value beyond the schema by explaining the identification modes: 'Identify the filing with filing_id, or ticker + fiscal_year (+ optional quarter)' and clarifying that quarter is 'only needed to disambiguate quarterly filings.' This gives agents a decision procedure the schema alone doesn't provide.

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: 'Return the filing's Cash Flow Statement — its extracted line items with values and periods.' It clearly distinguishes this from sibling statement tools (balance sheet, income statement) by naming the statement type, and further differentiates itself from get_filing_statement by framing itself as a fixed shortcut that 'does not take role_label or statement_type.'

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 explicitly names the alternative get_filing_statement and explains the relationship: 'A fixed shortcut for get_filing_statement(statement_type='Cash Flow Statement')' with the key exclusion that it does not accept role_label or statement_type. It also gives identification requirements (filing_id vs ticker + fiscal_year) and the SEC-only limitation. It doesn't exhaustively enumerate when to use other statement tools, but the main routing decision is clearly covered.

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