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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is covered structurally. The description adds nothing on top of that: no indication of what period is defaulted, whether results are aggregated, or what authorization/scope is required.

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?

Short, but the only substantive sentence is duplicated verbatim ('GET /api/expenses/period-overview' appears twice), which is pure waste. Brevity here reflects under-specification rather than disciplined editing.

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, 0% parameter coverage, and a nested free-form 'query' object, the description carries the full explanatory burden and discharges none of it. The redirect to describe_operation is the only mitigation, leaving the agent unable to call this correctly without a second round trip.

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 two parameters ('query' as an open additionalProperties object and an empty 'params' object) are entirely undocumented. The description offers no parameter meaning at all, so an agent cannot know what belongs in 'query' for this endpoint.

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 title verbatim ('GET /api/expenses/period-overview'), giving no human-readable explanation of what a 'period overview' contains or returns. Against siblings like get_expenses_contract_period_overview, get_expenses_summary, and get_expenses_trends, an agent has no basis for choosing this one beyond the raw path string.

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 statement of when to use this endpoint versus the many other expense endpoints (summary, trends, dashboard, contract period overview). The only routing hint is a generic pointer that 'describe_operation provides native request schemas', which is an operational note, not usage guidance.

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