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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value by disclosing the return content (per-category budgeted vs actual), the forecast-period scoping, and the roll-up behavior. It stops short of noting edge cases such as users with no configured budget, so it is strong but not exhaustive.

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?

Three sentences, front-loaded with purpose and return shape, followed by sibling routing and the page-link pairing. Every sentence carries distinct information and none repeats the annotations.

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, and the description compensates by describing the per-category entry structure and the roll-up effect on it. For a two-parameter read tool with full annotation coverage, an agent has everything needed to call it and interpret the result.

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%: both user_id and roll_up are fully documented, including roll_up's default and its non-obvious behavior of keeping children visible while folding figures into parents. The description's 'Optionally rolls up child categories into their parents' only restates that, so 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 specific verb and resource ('Gets the user's budget') plus the scope ('configured forecast period') and the exact return shape ('one entry per category with budgeted vs actual figures'). It is clearly distinguishable from get_budget_summary and navigate_to_budget without opening either schema.

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?

Explicitly routes the agent: use get_budget_summary for analysis over a specific date range, and offer navigate_to_budget as the matching page link. Both alternatives and the conditions selecting them are named, leaving nothing to inference.

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