get_account_statements

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

With no annotations, the description carries the full burden and does add real context: the returned fields (downloadUrl, startDate, endDate, endingBalance, accountNumber, EIN), the account-type eligibility restriction, and the 3-month range limit. It stops short of disclosing auth requirements, rate limits, or pagination behavior, which keeps it below a 5.

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?

Three front-loaded sentences: purpose first, then return payload, then the exclusion and range constraints. Every sentence carries operative information and there is no filler.

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, but the description enumerates the returned fields, and no annotations exist to cover constraints, so the description must carry that load — which it largely does. The remaining gap is pagination/cursor behavior for end_before/start_after, which is left to the schema.

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 100%, so the baseline is 3 and the schema already documents accountId, start, end, limit, order, and paging cursors. The description adds a constraint not present in the schema (the 3-month maximum range for start/end), which meaningfully augments the parameter semantics.

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 ('Retrieve monthly statements') and scopes it to 'a specific Mercury account'. It explicitly contrasts with the sibling get_treasury_statements and rules out treasury/credit accounts, so an agent can distinguish it without opening the schema.

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?

Gives an explicit when-not-to-use ('treasury and credit accounts are NOT supported'), names the alternative tool to use instead, and states a hard usage constraint (max 3-month range via start/end). This is exactly the when/when-not/alternatives guidance required.

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