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

Annotations already declare this as read-only, idempotent, and non-destructive, covering the safety profile. The description adds 'optional search' but this is also present in the input schema. No additional behavioral context (e.g., return format, pagination) is provided, but the annotations alleviate the need for safety disclosure.

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, concise sentence that immediately conveys the action and optional search. There is zero waste, and the most important information is 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?

For a simple list tool with two optional parameters and no output schema, the description is adequate. It does not explicitly state that it returns all contacts when no search is supplied, which is a minor gap, but overall it provides enough context for an agent to invoke the tool correctly.

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% with clear descriptions for both 'limit' and 'search'. The tool description does not add any meaning beyond the schema, but per the rubric, a high coverage baseline yields a score of 3.

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 'List contacts with optional search' uses a specific verb (list) and resource (contacts), clearly distinguishing it from sibling tools like get_contact (singular) and create/update/delete_contact. It also hints at the optional search functionality, making the tool's purpose unambiguous.

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 implies usage for listing contacts, but does not explicitly state when to prefer this over get_contact or when not to use it. There is no mention of alternatives or exclusions, so usage guidance is only implied by the plural 'contacts' versus the singular sibling.

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