add_party_phone_number

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

The description mentions it's atomic and uses one PUT to Capsule, which gives some insight into the operation's behavior. However, without annotations, it lacks details on permissions, side effects, or reversibility, which is minimal but acceptable for a simple append.

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, front-loaded with the action verb, no redundancy. Every word adds value, making it highly concise and structured.

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 the complexity (3 parameters, no output schema, no annotations), the description provides purpose and usage but lacks coverage of parameter details and return value. It partially compensates for missing schema descriptions but is not fully complete.

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 coverage is only 33% (only 'type' has a description), and the description does not add any extra meaning to the parameters like 'partyId' or 'number'. The tool's purpose is clear, but parameter details are left entirely to the schema, which is insufficient.

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 action ('Append a single phone number to a party') and distinguishes it from the sibling tool 'update_party.phoneNumbers' by noting it's for single-entry adds, making the purpose precise.

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?

Explicitly recommends using this tool instead of 'update_party.phoneNumbers' for single-entry adds, providing clear context for when to use it. No exclusions are mentioned, but the guidance is sufficient.

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