GetMonth

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower, yet the description adds real nuance: hidden categories are excluded from the list and their combined amounts land in omitted_hidden_categories, and internal categories are system rows, not budget lines. That is genuinely useful context beyond the structured fields.

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 short paragraphs, front-loaded with the field inventory and followed by the caveats an agent needs. Every sentence carries information; the return-field list is dense but the useful caveats come before the routing line.

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?

With annotations, a full output schema and 100% schema coverage, the description only needs to frame scope and edge cases, which it does via the hidden/internal-category notes. It is complete for correct invocation, though the field enumeration partly restates what the output schema already provides.

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 month, plan_id (including the 'last-used' default and ListPlans pointer) and include_hidden are already fully documented. The description alludes to hidden-category handling but adds no parameter syntax or format detail beyond the schema, matching the baseline 3.

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?

Names a specific verb and resource ('Get one plan month') and enumerates exactly what it returns: Ready to Assign, age of money, income, totals, and per-category assigned/activity/available plus goal progress. This clearly separates it from the plural sibling Ynab_ListMonths 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?

The closing line gives an explicit usage cue ('best single call for "how is my budget doing this month?"'), which tells the agent when this beats narrower calls like GetCategory or ListMonths. It stops short of naming alternatives or stating exclusions, so it is clear context rather than full routing guidance.

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