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

The readOnlyHint annotation already conveys safety. The description usefully discloses the return payload (line items with prices, quantities, categories), which adds value beyond annotations, but it omits error behavior (e.g., what happens if the ID is not found) and any pagination or size considerations.

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?

One tight sentence that front-loads the action and ends with the most valuable detail (the return contents). No fluff.

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 simple one-parameter read tool with a clear annotation profile and no output schema, the description adequately explains what is returned. Minor gap: error behavior and whether the line-item list could be large are unstated.

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% and the single parameter (expenseId) is fully documented in the schema. The description adds no extra semantics about the ID format or source. Baseline 3 applies.

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 (get) and resource (expense detail by ID) and describes the return contents. It is clearly distinguishable from list-oriented siblings like get_expenses and search_expenses, though it doesn't name them explicitly.

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 single-item/by-ID scope is implied but there is no explicit guidance on when to use this vs. get_expenses or search_expenses, nor any note on error behavior for invalid IDs.

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