Budget vs actual

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, so safety is covered; the description adds the direction convention (spending positive, utilization_pct>100 = over budget), the single-request cost, and 'changes nothing'. That is meaningful operational context beyond the annotations. It stops short of mentioning pagination or freshness of the data, so not a 5.

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?

Front-loads the core calculation, then answers the question this serves, then the routing alternatives, then the unit conventions. Four short sentences with no redundancy.

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 2-param read-only tool with an output schema and full annotation coverage, the description supplies the orientation (question it answers), the alternative-tool split, and the number conventions. Nothing an agent needs to call it correctly 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 description coverage is 100% and the schema already documents both month and plan_id formats, so the description adds little parameter-level detail. Baseline 3 applies when structured fields do the heavy lifting.

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+resource: computes the share of each category's budget spent in a month, with the explicit goal of revealing over/close-to-limit categories. It also names three sibling tools (get_category_balances, get_monthly_summary, get_spending_trends) and the distinct question each answers, so an agent can pick this tool without opening any 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?

Explicit when-to-use framing ('am I over budget?', 'which categories are nearly used up?') plus three named alternatives each tied to a different intent. This is textbook routing guidance.

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