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 one genuine behavioral constraint — results are not currency-converted or combined — but omits the more consequential behaviors, such as what scope of data is read and what happens when no month is supplied.

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?

One sentence with zero filler, and the comparison semantics and currency caveat are front-loaded. Nothing needs trimming.

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 no output schema and 0% schema coverage, the description carries the full burden and falls short: it never explains what the returned comparison looks like, what 'approved spending' means, or how the nullable month filter behaves. For a reporting tool this leaves meaningful gaps.

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 0% and the single parameter is a nested object whose 'month' field is nullable with a default of null and a YYYY-MM pattern. The description says nothing about this parameter, so the critical question — does null mean all months? — is left entirely unanswered.

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 concrete operation (compare approved spending against monthly budgets) on a named resource, which is more informative than the tautological title. It does not, however, distinguish itself from siblings like get_budget, list_budgets, or get_spend_summary, leaving the agent to guess which is the budget-vs-actual view.

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?

There is no guidance on when to call this versus get_budget or get_spend_summary, no prerequisite or scope information, and no exclusions. The agent must infer usage purely from the tool name.

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