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

Beyond the read-only and idempotent annotations, it discloses that the target is a spreadsheet-style table, that future months show forecast only, and that the date pair can span multiple years in the past or future. It also warns that named ranges are not resolved, which is useful behavioral context for correct invocation.

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 front-loaded with purpose and destination semantics, and the usage examples are valuable. It is slightly repetitive around the explicit start_date+end_date requirement, but otherwise dense and task-focused.

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?

Given a navigation tool with no output schema and fully described input schema, the description is complete: it explains the destination view, the forecast-vs-actual behavior, date-range constraints, and when to choose sibling navigations instead. Nothing critical for correct selection or invocation is missing.

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 coverage is 100%, so the baseline is 3. The description still adds useful meaning by stating that start_date and end_date are required together, define month columns, can span any horizon, and do not accept named ranges, though it leaves account_ids and scenario_ids mostly to 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?

The description gives a specific verb and resource: 'Deep link to the Cashflows statement (/cashflows)'. It also explains the destination is a month-by-month table, not a chart, and names sibling navigations it is distinct from.

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?

It explicitly says to pick this for projection, affordability, and liquidity asks, with concrete example questions such as 'what will my balance be at Christmas'. It also routes the agent away to navigate_to_income_expense, navigate_to_trends, navigate_to_net_worth, and navigate_to_calendar for adjacent use cases.

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