list_trusted_contacts

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the description only needs to add context. 'Without phone numbers' is a genuinely useful disclosure: it warns the agent that the result cannot be used to obtain contact phone numbers, which would otherwise be a false assumption.

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?

A single sentence with no filler, and the caveat about phone numbers is placed where it will be read. Nothing could be removed without losing information.

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 zero-parameter read tool with full annotations and no output schema, the essentials are covered. However, the description never indicates what the returned contacts contain (names, IDs, aliases) or whether those values are the inputs expected by send_trusted_message, leaving a gap for chaining with siblings.

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 tool takes zero parameters, so the baseline is 4 and there is nothing for the description to compensate for. The schema's empty properties object matches the description's lack of input discussion.

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 (List) and resource (pre-approved contacts), and distinguishes itself implicitly from the write-oriented sibling send_trusted_message. It stops short of naming an alternative or clarifying what a 'pre-approved' contact is relative to the other contact-handling tools.

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 no when-to-use guidance, no exclusions, and does not mention any sibling such as send_trusted_message or prepare_handoff. The agent must infer the retrieval workflow entirely from the tool name.

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