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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds meaningful context beyond that: the pdf-vs-csv output behavior, the RESOURCE_NOT_FOUND condition for unissued months, and the session/credit-line requirement. It stops short of describing pagination or rate limits, but covers the key behavioral traits.

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 description is two compact sentences, front-loads the core purpose, and packs format behavior, error conditions, and auth requirements without any redundant wording.

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?

With no output schema, the description adequately explains what is returned for each format, the error case for invalid months, and the session prerequisites. An agent has everything needed to call it correctly.

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 baseline is 3. The description adds value by explaining that `period` is YYYY-MM, that `format` defaults to pdf and produces an embedded file, while csv returns text in the `csv` field — semantics not fully conveyed by the terse schema descriptions.

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 ('Returns the signed-in partner's own monthly statement of account') with scope and format behavior, making it clearly distinct from siblings like get_credit_line_statement and list_settlements.

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?

Explicitly states the conditions under which the tool works: statements exist only for issued months, otherwise RESOURCE_NOT_FOUND, and a signed-in partner credit-line session is required. It does not name alternative tools for other statement types, but the usage context is clear.

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