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

With no annotations, the description carries behavioral disclosure itself. 'Deterministic... same period, same bytes' discloses reproducibility, 'append-only ledger' implies no mutation, and 'Auth required' states the permission prerequisite.

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?

Two short sentences front-load the key behavior and add auth context. Every word contributes; no filler or repetition of schema fields.

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 low-complexity getter with three fully documented parameters and no output schema, the description is nearly complete: purpose, determinism, source, and auth requirement are present. It does not cover error/edge-case behavior, but that is less critical here.

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% and the input schema already describes wallet, period, and format with defaults. The description adds context about determinism but no additional parameter-level meaning.

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?

Description names a specific resource ('monthly statement') and a concrete behavior: it is derived deterministically from the append-only ledger. This clearly distinguishes get_statement from sibling get_balance/get_delegation/get_policy tools.

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?

The description implies when to use it (when a reproducible monthly statement is needed) and notes that auth is required, but it does not explicitly state when not to use it or name alternatives among the many get_* siblings.

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