List contacts

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

Beyond the annotations (readOnlyHint, idempotentHint, destructiveHint), the description discloses useful behavioral details: returns a compact field set by default, the fields parameter can request ['all'], the exact pagination response shape, and the fact that monetary values are integers in cents. This adds significant value beyond the annotations without contradicting them.

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 concise and well-structured: it opens with the core purpose, then the key prerequisite, and finally the return format and pagination hints. Every sentence adds value, with no redundancy or filler.

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 there is no output schema, the description does a great job explaining the return shape, pagination, and data format. It covers the required parameter (customer_id), pagination, fields selection, and monetary units, making it sufficiently complete for an agent to use correctly.

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 coverage is 100%, so the schema already documents each parameter well. The description adds extra meaning by explaining the compact default field set, the use of ['all'], and the cents-based monetary values, which are not in the schema. The 'optional filters' mention is slightly misleading but does not heavily impact parameter understanding.

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 'List contacts from easybill' with a specific verb and resource, and it distinguishes itself from the sibling 'easybill_get_contact' by focusing on listing rather than retrieving a single contact. It also adds essential scope information: 'Contacts are always scoped to one customer, so customer_id is required.'

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 when to use the tool: it requires a customer_id and explains pagination via next_page. However, it does not explicitly mention alternatives like easybill_get_contact for fetching a single contact, and the phrase 'optional filters' is somewhat vague since the schema includes no actual filter parameters beyond pagination/projection.

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