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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed-world scope, so the safety profile is covered. The description does add value by enumerating the returned fields, which matters because there is no output schema, but it says nothing about what happens for an unknown expense_id or whether the lookup is scoped to a company/project.

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 short sentence with no filler, and the returned-field list is front-loaded. It is efficient, though the missing verb means the brevity comes partly at the cost of clarity.

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 single-entity read tool with full annotation and schema coverage, the essentials are present and the field list substitutes for a missing output schema. It still omits any statement of error behavior or scope limits that would make the definition fully self-sufficient.

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?

There is a single parameter with 100% schema description coverage, so the schema already explains that expense_id comes from list_expenses. The description adds nothing about the identifier's format or provenance, leaving the baseline 3 appropriate.

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 phrase 'One expense with amount, date, vendor...' implies fetching a single expense record, but it never states a verb and reads as a field inventory rather than a purpose statement. It loosely distinguishes itself from list_expenses by saying 'one', but an agent must infer that this is the single-record counterpart.

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 guidance on when to use this versus list_expenses or the other get_* siblings. The only routing hint lives in the schema ('expense_id from list_expenses'), not in the description, so the description itself gives no alternatives or preconditions.

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