月度统计

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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds genuinely useful behavioral context beyond that: the month defaults to the current month in UTC+8, and results are compared against the previous month — both affect how an agent interprets the output and are not derivable from the schema or annotations.

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 short sentences with no filler; the metric enumeration is dense but every listed item is meaningful content the agent needs. The default-month rule is placed at the end rather than front-loaded, a minor structural miss.

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, the description carries the return-content burden, and listing the aggregated fields plus the prior-month comparison largely does that. What remains unstated is the response shape (flat object vs nested per-section) and whether the comparison is a delta or two values.

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%, so the YYYY-MM format and default are already documented, giving a baseline of 3. The description adds the timezone qualifier for the default (东八区), which the schema omits and which materially changes what 'current month' means for an agent.

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?

The description names a concrete verb+resource (按月汇总 / monthly aggregation) and enumerates the exact metrics it computes: purchases, bookkeeping, income, net expense, installment due, budget usage, category TOP, status counts, plus a month-over-month comparison. That is far more specific than the sibling CRUD tools, though it never explicitly separates itself from budget.get, which is the nearest overlap.

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?

Usage is implied rather than stated: an agent can infer this is the read-only overview tool for a given month. There is no explicit when-to-use versus budget.get or the list tools, and no stated exclusions or prerequisites, so routing still requires some inference from the metric list.

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