Who am I: cashier and organization

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds real value by disclosing the content of the response (including the is_test flag and organization tax/VAT/offline/SMS settings), which is meaningful since no output schema exists. It omits auth requirements and any caching/rate-limit behavior.

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?

Front-loaded with the action and subject, followed by a short imperative sentence telling the agent when to call it. The parenthetical field list is dense but earns its place because no output schema documents the return shape.

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?

With no parameters and no output schema, the description carries the full burden of describing the return value and does so across both the cashier and organization objects. It is complete enough to call correctly, though it could note whether organization data is always present.

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 takes zero parameters, so the schema imposes no semantic burden and the baseline for a no-param tool is 4. The description correctly implies a no-argument call by framing the result as the server's own identity.

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?

States a specific verb and resource ('Returns the cashier this server is signed in as') and enumerates the returned payload (name, permissions, signature type, is_test, organization fields). This clearly separates it from siblings like get_cash_register or get_current_shift, which operate on registers and shifts rather than identity.

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?

'Call this first to learn whose data the other tools will show' gives explicit ordering guidance and a clear context in which the tool is useful. It stops short of naming a when-not condition or an alternative, but no plausible alternative exists for an identity endpoint.

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