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

Annotations already cover readOnlyHint, idempotentHint, and destructiveHint. The description adds value by disclosing the returned fields, per-currency totals, and the behavior around the 30-day free read window. There is no contradiction with 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 concise sentences with the main purpose and output details front-loaded. The free-tier explanation is compact and meaningful. No filler or redundant restatement of the tool name.

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 usefully explains the return shape and the free-tier date limitation. It omits pagination and ordering details, but these are minor for this kind of listing tool given the description's otherwise clear scope.

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 40%, covering just to/from. The description mentions date-range filtering and lists category/project/billable as fields, but it does not clarify that project, billable, and category are optional filters, their allowed values, or how they interact. It therefore does not adequately compensate for the low schema coverage.

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 the operation and resource clearly ('List expenses') and adds specific detail about the returned data: net/VAT split, category, merchant, project, billable flag, and total per currency. It distinguishes itself from a summary or export implicitly, though it does not explicitly name a sibling tool.

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?

The description implies the intended use is retrieving expense records within a date range, and it adds a meaningful note about the free 30-day read window. However, it does not explicitly state when to prefer expense_summary, expense_export, or other sibling tools, nor does it provide exclusions.

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