list_billable_items

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

With no annotations, the description carries the full burden. It only notes 'Fails loudly' without specifying conditions or disclosing whether the operation is read-only, what auth is needed, or the nature of 'challenge tokens'.

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 very concise with two sentences and no fluff, though the version note could be moved to reduce front-loading of non-essential info.

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?

Given the tool has an output schema, return values are covered. However, the description leaves significant gaps around failure conditions, challenge tokens, and how to handle the 'fails loudly' behavior, making it barely adequate for an agent.

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%, and the description does not add meaning beyond the schema's property names. 'to_date' is unexplained, and 'matter_id' is only indirectly mentioned.

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 clearly states the action ('Preview'), resource ('unbilled billable items'), and scope ('for a matter'), distinguishing it from sibling tools like list_invoices or list_expenses.

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?

Usage context is implied for previewing unbilled items, but no explicit when-to-use or when-not-to-use guidance is given, nor are alternatives mentioned.

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