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

readOnlyHint=true already establishes this as a safe read. The description adds that Codat rejects calls without both period parameters, plus the underlying endpoint (GET /companies/{companyId}/data/financials/cashFlowStatement), which is useful for debugging. It says nothing about pagination, rate limits, or what a company with no synced financials returns.

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?

Two tight sentences with the core action front-loaded and the constraint second. The trailing endpoint reference is mildly redundant with the tool name but is compact and arguably aids debugging, so it does not seriously bloat the definition.

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?

There is no output schema, so the description has to carry the return-value burden; 'broken into periods' only sketches the shape. For a financial reporting tool an agent would still benefit from knowing the period granularity/response structure and behavior on missing data, which is not covered.

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 every parameter (companyId, startMonth, periodLength, periodsToCompare) is already documented with ranges and defaults. The description only echoes the required status of two of them, adding no new syntax, format, or interaction detail beyond the schema.

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 specific verb and resource ('Get a company's cash flow statement') and adds the shape of the result ('broken into periods'). Siblings like codat_get_balance_sheet and codat_get_profit_and_loss are clearly the same family of financial statements, so the resource noun alone distinguishes this one.

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 notes that periodLength and periodsToCompare are BOTH required by Codat, which is a usage precondition, but it never says when to reach for the cash flow statement versus the balance sheet or P&L, nor any when-not guidance. Usage is implied by the financial-statement name rather than stated.

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