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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered structurally. The description adds no behavioral context beyond that - no mention of aggregation behavior, time granularity, or response shape - and does not contradict the 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?

The single content sentence is duplicated verbatim, wasting half the text, and the operation ID plus boilerplate add nothing for an agent. There is no front-loaded statement of purpose to concisely structure around.

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 nested objects, an untyped open-ended query parameter, no output schema, and no annotations explaining aggregation semantics, the description leaves an agent unable to call this correctly. Nothing about accepted query fields or what the trends contain is provided.

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 description supplies nothing about the two parameters (a free-form 'query' object and an empty 'params' object). It defers entirely to describe_operation, which forces an extra round trip rather than explaining accepted filter keys or formats.

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 only restates the tool's HTTP path twice ('GET /api/expenses/trends'), which is a tautology of the name and title. It never explains what an 'expenses trend' is (time series? category breakdown? period comparisons?) nor how it differs from siblings like get_dashboard_expense_trends or get_expenses_summary.

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?

No guidance whatsoever on when to use this tool versus the many nearby expense/dashboard tools. The only directive is an unrelated pointer to describe_operation for schemas, which does not help an agent choose between alternatives.

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