Get customer

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

Annotations already declare read-only and idempotent hints. The description adds useful behavioral details: 'returning all fields by default' and 'Monetary values are integers in cents (150 = 1.50 EUR)', which are not present in the annotations. No contradictions.

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?

Three concise sentences: the first states the core purpose, the second provides an alternative, and the third gives a parameter tip and a data format warning. No extraneous content; front-loaded with the most important information.

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 simple get-by-id tool, the description covers when to use, the default return behavior, and a key data format detail. With no output schema, the monetary unit clarification is valuable. It could mention response_format or error cases, but the schema covers the former and the tool is straightforward.

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 description covers 100% of parameters, so baseline is 3. The description does not add significant parameter semantics beyond the schema; it only repeats the 'fields' narrowing concept. The monetary value hint is about return data, not parameters.

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 states 'Fetch one customer by its numeric easybill ID' with a specific verb, resource, and method. It distinguishes itself from siblings by noting that easybill_list_customers should be used when only a name or number is known.

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?

Explicitly says 'Use easybill_list_customers first if you only know a name or number', giving an alternative for different lookup scenarios. Also advises using 'fields' to narrow the response, providing clear usage context.

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