create_book

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

No annotations are provided, so the description carries the behavioral burden. It discloses that the tool creates a resource ('Initialise'), that the book is 'empty' and 'git-backed', and that it errors on duplicate creation. This goes beyond a bare 'create' statement and gives the agent useful operational expectations.

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 extremely concise: two sentences, with the core action front-loaded and the key constraint in a single follow-up sentence. Every word adds value and there is no redundant or filler content.

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 simple creation tool with two optional parameters and an output schema present, the description covers the essential behavior and a critical failure mode. It could be slightly more complete by clarifying the meaning or allowed formats of 'name' and 'currency', but overall an agent has enough context to invoke 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?

The input schema provides only parameter names ('name', 'currency') with defaults but no descriptions, and the description does not explain either parameter. While the names are somewhat self-explanatory in context, the description adds zero semantic detail, leaving the agent to infer what values are appropriate for each optional parameter.

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 ('Initialise') and a concrete resource ('a new, empty cloud book (git-backed Beancount ledger)'), making the tool's function immediately clear. It also implies the distinction from the sibling connect_book, which targets existing books, so an agent can tell them apart.

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 gives a clear usage constraint: 'Safe to call once per book; errors if a book already exists at the location.' This tells the agent when to invoke it (creation) and warns against duplicate calls, though it does not explicitly name connect_book as the alternative for existing books.

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