Add a contact

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

The description adds no behavioral context beyond the annotations (openWorldHint, idempotentHint). It does not disclose side effects such as contact approval flows, duplicate handling, or the purpose of addPhonePrivacyException, leaving the agent with minimal behavioral understanding.

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 sentence, making it extremely concise and front-loaded with the core action. It contains no wasted words, though its brevity also contributes to under-specification.

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 six parameters, no output schema, and minimal annotations, the description is far too terse to be complete. It fails to explain parameter purposes, return behavior, or special conditions such as phone being required for contact lookup, leaving significant gaps for the agent.

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?

The schema covers only 17% of parameters with descriptions (only 'phone'), and the tool description mentions no parameters. The implied meaning of 'user' is insufficient to explain required fields like firstName/lastName, accountId, and addPhonePrivacyException, making the description unhelpful for 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 uses a specific verb 'Add' and clearly identifies the resource as 'a user to your contacts', distinguishing it from sibling tools like list_contacts, delete_contact, and search_contacts. It is unambiguous and directly states the tool's function.

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 provided on when to use this tool versus alternatives. It does not mention prerequisites like authentication, how to obtain the 'user' parameter, or when to prefer search_contacts or block_user over adding a contact.

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