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

Annotations already cover read-only, idempotent, non-destructive behavior. The description adds meaningful context beyond annotations: it requires OAuth or a scoped credential, and it has an API key requirement and cost. This helps an agent decide whether it can invoke the tool.

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 compact and front-loaded: it states the core summary content first, then adds auth and cost requirements. Every sentence provides useful information with no redundancy.

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 zero-parameter read-only tool, the description is complete: it names the resource, the data included, and the required credential. The presence of an output schema means return-value documentation does not need to be duplicated in the description.

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 tool has zero parameters and the input schema is empty, so there is no parameter semantics burden on the description. The description appropriately communicates that the call is pre-scoped to the authenticated user and requires no further arguments.

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 identifies the resource (authenticated user cashflow summary) and the specific fields returned (spend, income, net, top spend categories). It is distinct from sibling tools like get_people or get_events, which cover different domains.

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 clearly states the context: it returns a cashflow summary for the authenticated user. It also notes the credential requirement. It does not name alternative tools for expense-related queries, but no direct expense sibling exists, so the context alone is sufficient.

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