expensify_create_expense_rule

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

Annotations already indicate write and destructive behavior. The description adds the important note that dry-run is enabled, so it previews only, which clarifies current behavior. However, it does not disclose other behavioral traits like error handling or necessary permissions.

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 with two sentences. The first sentence states the purpose, and the second sentence provides critical usage context (write and dry-run). No unnecessary words.

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 3 required parameters including a nested object and no output schema, the description is incomplete. It lacks information about what the dry-run preview returns, prerequisites (e.g., valid policy and employee), and any side effects beyond the dry-run note.

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 coverage is 67%, leaving the 'actions' object partially described. The description adds meaning by referencing 'tag or billable status,' which maps to two subproperties. However, it does not enrich the understanding of policyID or employeeEmail beyond the schema descriptions.

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 (create), the resource (expense rule), and its purpose (apply tag or billable status for an employee on a policy). It distinguishes from other create tools like creating expenses or reports, but does not explicitly differentiate from the sibling tool expensify_update_expense_rule.

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 no guidance on when to use this tool versus alternatives. It mentions 'Dry-run is currently ON' but does not explain under what circumstances to use this tool or when to use the update sibling instead.

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