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

Annotations already cover the read-only, idempotent, non-destructive profile, and the description adds genuinely useful behavior beyond them: the download link expires after one hour, and the output document's layout is specified (A4, titled STATEMENT OF ACCOUNT, chronological movements, BALANCE OUTSTANDING at foot). 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?

Three sentences with the purpose front-loaded and the output format summarized compactly. The trailing 'Pro.' is terse and slightly cryptic, and the layout details, while useful, could arguably be trimmed, but overall every sentence contributes and the description is efficiently sized.

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 read-only render tool with fully documented parameters and no output schema, the description covers purpose, deliverable form, and link expiry sufficiently. It does not explain return-value structure or error cases, but these are not required given the tool's simplicity and the annotation coverage.

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 the schema already fully documents all six parameters; the description adds no per-parameter meaning beyond what the schema provides. Baseline 3 is appropriate since the description does not need to compensate for schema gaps.

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 states a specific verb and resource ('render one client's A4 statement of account') and adds a concrete deliverable detail (download link valid for one hour). It partially distinguishes from siblings via 'one client's', which implies batch tools like statements_report are different, but it never explicitly names or contrasts with statement_build, so full sibling differentiation is missing.

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?

'Call this tool to render one client's A4 statement of account' gives clear, directly actionable context for when the tool applies. The phrase 'one client's' implies a boundary against multi-client alternatives, but there are no explicit when-not conditions or named alternative tools, so it falls short of full 5-level guidance.

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