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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered; the description adds genuinely useful non-obvious behavior: 'Returns one currency per expense and never converts' and an auth requirement ('Needs the user's Cotlet API key with access to this app'). It still omits pagination behavior hints beyond the cursor parameter, but the extra disclosure is meaningful.

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 content is front-loaded with the resource and returned fields, but 'newest first' is stated twice in the first two sentences and the opening 'Expenses with merchant, amount...' clause is a fragment that partly restates the following sentence. It is usable but not tight — noticeable redundancy against a fairly short text.

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?

No output schema exists, so the description carries the return burden and does so by enumerating returned fields and the single-currency rule; it also covers auth. It is nearly complete for a read-only list tool, with only pagination/volume guidance left thin.

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%, so every parameter is already documented (limit range, since/until, cursor, on_report, has_receipt, workspace). The description restates the filter dimensions but adds no syntax, format, or default detail beyond the schema, which is the correct baseline 3 when the schema does the heavy lifting.

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 and resource ('Lists expenses in your account') and enumerates returned fields (merchant, amount, category, receipt flag, report) plus ordering ('newest first'). This clearly separates it from expensify_list_reports, though it never names the sibling explicitly, and the opening clause duplicates the later 'newest first'.

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?

It sketches available filters ('Filter by date, by whether they are on a report and by whether they have a receipt') and hints at use ('Held expenses are marked, so you can leave them out of a report'), which is implied usage guidance. There is no explicit when-to-use vs alternatives routing — nothing tells the agent to prefer this over expensify_get_expense or list_reports.

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