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

Beyond the annotations (which only mark it as a non-destructive, open-world write), the description discloses that it returns a client_id, that it deliberately skips confirmation because a wrong entry is correctable in Facturama, and that it requires a Cotlet API key with app access. These are real behavioral traits the annotations do not convey.

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 target, followed by the highest-value disambiguation (no notifications, no invoice) and the auth requirement. Slightly dense but every sentence carries information; no padding.

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 mutation tool with no output schema, the description usefully notes the returned client_id and states the auth prerequisite. It stops short of explaining duplicate handling or what identifying constraints Facturama enforces, but it is otherwise complete enough to call 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 coverage is 100%, so each field (rfc, name, cfdi_use, tax_zip_code, fiscal_regime) is already documented in the schema. The description restates the same field list without adding format, validation, or default semantics, so the baseline 3 applies.

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 ('Add a client') and resource ('catalog'), and enumerates the identifying fields (RFC, name, CFDI use, tax zip code, fiscal regime). This clearly separates it from facturama_get_client and facturama_list_clients, which read existing clients.

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 gives clear context by stating what the tool does NOT do ('reaches no one and issues nothing'), which implicitly routes the agent away from facturama_email_invoice and facturama_create_invoice. No explicit 'use X instead when...' alternative is named, so it falls short of a 5.

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