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

Annotations already declare readOnlyHint=false, destructiveHint=true, and openWorldHint=false, so the safety profile is covered structurally. The description adds real behavioral context by conveying partial-update semantics (unspecified fields are left alone), but it never explains the destructiveHint flag — whether updates are reversible, or what happens to existing budget/transaction data when a field is rewritten.

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?

Two tight sentences with no filler, and the core action is front-loaded before the sending instruction. It is appropriately sized, though the second sentence could carry a little more weight given how undocumented the parameters are.

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 six-parameter mutation tool with no output schema and very thin schema descriptions, the description is too sparse: it does not enumerate updatable fields, note that budgetId is required and immutable, or warn about the destructive hint. An agent would need to infer almost everything from the raw schema.

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 only 17% — just endDate carries a format note — while five other parameters (amount, period, budgetId, isActive, alertThreshold) have no textual explanation anywhere. The description says what to send but never enumerates or explains the updatable fields, so it fails to compensate for the coverage gap. The patch instruction is the only added meaning.

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 — "Update fields of a personal budget" — so an agent can tell it is a mutation on the budget resource rather than a goal, transaction, or group. It does not distinguish itself from siblings like update_goal or update_personal_transaction beyond the resource noun, so sibling differentiation is only implicit.

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?

"Only send the fields to change" is genuinely useful patch-style guidance and implies the tool is for partial modification rather than replacement. However, there is no when-to-use/when-not guidance relative to create_budget, delete_budget, or list_budgets, and no prerequisites such as ownership or permission requirements.

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