sw_create_expense

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

With no annotations provided, the description fully discloses the critical side-effect behavior: 'Without confirm:true this returns a dry-run preview and makes NO network call; with confirm:true it creates the expense.' This alerts the agent to the mutation risk and the preview safety mechanism, going well beyond what schema alone provides.

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 two concise sentences that cover purpose, usage modes, formatting constraints, and the critical confirm gate. Every clause earns its place with no fluff or repetition, making it easy to parse quickly.

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 create tool with no output schema and 10 params, the description distills the essential context: how to split, what cost requires, and the preview vs. real-creation distinction. The remaining optional params (date, currency_code, etc.) are adequately described in the schema, so the tool is fully usable with this description alone.

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 schema has 100% parameter coverage, providing baseline 3. The description Adds meaningful operational nuance by framing the split_equally vs users decision and reiterating the cost format. However, most parameter details (e.g., decimal strings, mutual exclusivity) already appear in the schema, so the added value is modest but helpful, warranting a 4.

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 'Create a Splitwise expense', which uses a specific verb and resource, clearly distinguishing it from sibling tools like sw_update_expense or sw_delete_expense. It also outlines the key operational modes, leaving no ambiguity about the tool's core function.

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 provides clear context on how to use the tool: 'Use split_equally:true to split evenly... or provide a users array for custom per-person splits.' It also explains the crucial confirm:true gate. However, it does not explicitly name alternative tools or state when not to use this tool, so it misses the 'explicit alternatives' bar for a 5.

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