add_expense

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

No annotations are provided, so the description bears full burden. It discloses core functionality and split options but omits details on error handling, permissions, or side effects. The examples for split_map are helpful but do not cover all potential issues.

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 well-organized with an Args section and examples. It is concise yet informative, though the verbose Example formatting could be slightly more compact.

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 number of parameters (7) and no annotations, the description covers most parameters and their relationships. The presence of an output schema likely covers return values. Minor gaps include lack of error scenarios and ordering constraints.

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?

With 0% schema coverage, the description compensates well: it explains amount as 'total cost', description as 'brief description', and provides explicit examples for split_map. However, some parameters like exclude_names lack contextual detail about how they interact with group splits.

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 tool's action: 'Add an expense to Splitwise', and highlights key features like unequal splits and groups. It distinguishes itself from siblings like delete_expense and list_friends.

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 includes parameter explanations and usage notes (e.g., friend_names can be empty if using group_name, split_map examples). It lacks explicit comparison to alternative tools but provides sufficient context for correct invocation.

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