Add a client

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

With no annotations, the description carries the full burden. It discloses two important behaviors: re-adding the same name updates stored details, and an identical record is refused with the id of the existing record. This gives useful idempotency and duplicate-handling context, but it omits return value, permission requirements, and whether other fields are cleared when updating.

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?

Two sentences with no fluff. The core purpose is front-loaded, and the behavioral nuance about update/duplicate refusal follows naturally. It is appropriately concise for a CRUD operation.

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 tool with no output schema, no annotations, and only 25% parameter coverage, the description is incomplete. It doesn't explain the response structure (e.g., the returned id), how updates affect unspecified fields, or any required permissions. An agent would need to make assumptions or call the tool to learn more.

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 only 25% (vat_id has a description). The description adds meaning for the 'name' parameter as the matching key for updates and duplicate detection, but it doesn't explain email, address, or vat_id beyond what the schema provides. Given the low coverage, the description should compensate more than it does.

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 verb 'Store a client' and the purpose 'so invoices can refer to them by name.' It is specific to client_add and distinguishes its upsert behavior from a plain create, though it doesn't explicitly contrast with sibling tools like client_delete or client_list.

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?

No guidance is given on when to use this tool versus alternatives. It doesn't mention client_list for viewing, client_delete for removal, or any prerequisite context. The agent must infer usage from the description alone.

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