list_contacts

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

Though no annotations exist, the description clarifies the data source (people/me) and OAuth scope. Implied read-only operation, but does not explicitly mention pagination behavior or other nuances. Absence of annotations makes description carry full burden; it adequately covers key behavioral aspects.

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?

Three concise sentences: purpose, alternative tools, and scope requirement. No extraneous information, well-structured and front-loaded.

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 tool's simplicity, with an output schema and fully described parameters, the description provides all essential context: purpose, usage guidance, and authentication requirements. No significant gaps.

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 parameters are well-documented in the schema. The description adds context that contacts are personal and from the authenticated user, which supplements the parameter meaning beyond the schema.

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 it lists the authenticated user's personal Google contacts from 'people/me', distinguishing it from sibling tools like list_contact_groups (groups), search_contacts (fuzzy search), and manage_contacts_batch (batch mutations).

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 provides when to use this tool vs alternatives, referencing sibling tools by name. Also specifies the required OAuth scope, setting clear usage context.

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