update_contact

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

Annotations already declare readOnlyHint=false (mutation) and openWorldHint=true (external side effects). The description adds one behavioral detail beyond annotations: specifying a phone number enables 2FA via SMS. However, it omits other important behaviors such as the confirm parameter needing to be true, and does not describe any error conditions or side effects beyond 2FA.

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 a single, focused sentence that front-loads the purpose and lists the key fields and the 2FA side effect. Every word earns its place; there is no fluff or redundancy.

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 update tool with 5 parameters fully described in the schema, the description covers the core functionality. However, it fails to mention the confirm parameter's requirement (must be true to execute), which is a critical execution guard, and it does not describe the return value or any failure modes. The absence of an output schema increases the need for such context.

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 all parameters are documented. The description merely restates which fields can be updated (email, password, phone) without adding format, constraints, or relationships beyond what the schema already provides. The 2FA note is also duplicated in the schema's phonenumber description, so it adds no new semantic value.

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 a specific verb ('изменить' = update) and resource ('дополнительный контакт' = additional contact), and lists the updatable fields (email, password, phone). This clearly distinguishes it from sibling tools like add_contact and delete_contact, and the mention of 'whmcs/update_contact' ties it to a specific API endpoint.

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 no guidance on when to use this tool versus alternatives such as add_contact, delete_contact, or update_billing_client. It does not mention prerequisites, exclusions, or the required confirm=true guard for execution. An agent would have to infer usage context from the name and schema alone.

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