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

The description discloses useful behavior: it finds recurring charges and ranks them by annual cost, and it indicates that output quality depends on having 90+ days of history. But with no annotations provided, it leaves gaps about exact return structure, read-only expectations, and edge cases like missing dates, so the description carries only part of the behavioral burden.

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 sentences with no filler: the first states the tool's purpose and behavior, the second gives the most important invocation guidance. Every clause earns its place, and the key purpose is front-loaded.

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 one-parameter tool, the description covers the required input shape, the best-practice data window, and the output ordering. It does not describe the full response object or explicitly address sibling alternatives, but it is largely sufficient for an agent to prepare and call the tool.

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 0%, so the description must compensate. It does by prescribing row contents as '(date, amount, description)' and recommending '90+ days.' It adds meaning beyond the bare schema, although it does not resolve the schema's optional date or specify date/amount formats.

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 opens with a specific verb and resource: 'Find recurring charges in a transaction list.' It further clarifies scope ('subscriptions, price-similar repeats') and output ordering ('ranked by annual cost'), which cleanly separates it from sibling tools like cash_runway or invoice_aging.

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 gives clear context and an actionable data-preparation guideline: 'Send 90+ days of (date, amount, description) rows for best results.' However, it does not explicitly mention when not to use this tool or name alternatives, so it stops short of a 5.

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