List contacts

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds meaningful context beyond annotations: it discloses that only summary properties are fetched (not full cards), that group cards are excluded by default and why, and that the operation is cheap. This exceeds what annotations 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?

Two sentences, front-loaded with the core behavior and outcome, then a cost/routing clarification. Every clause earns its place: the summary format, the cheapness rationale, and the pointer to get_contact are all necessary for correct tool selection.

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?

The description is complete for a read-only, idempotent listing tool with a rich schema and an output schema present. It explains the return style (short summaries vs full cards), the group exclusion default, the cost trade-off, and how to get the alternative behaviors via sibling tools. Nothing critical is missing.

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 the schema fully documents limit, address_books, and include_groups. The description adds context about why include_groups defaults to off and connects address_books to list_address_books outputs, but this is modest enrichment over a fully-covered schema. Baseline 3 is appropriate.

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 ('list') and resource ('contacts in one or more address books'), and immediately specifies what form the listing takes ('short summaries: name, organisation, addresses and phone numbers, and whether a photo is present'). This clearly distinguishes list_contacts from get_contact, which returns the whole card.

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 explicitly names get_contact and list_groups as alternatives and explains when to use them instead: get_contact for a full card, list_groups for proper group card reading. It also states the cost-saving rationale ('only the summary properties are fetched, so this stays cheap'). This is strong usage guidance.

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