list_contacts

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

With no annotations provided, the description carries the full burden, and 'Scope: contact:read' does add one behavioral trait: this is a non-mutating read operation requiring the read scope. However, it discloses nothing about response behavior — pagination, result limits, ordering, or whether full contact objects or summaries are returned — which matters for a listing tool.

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 clipped fragments — the operation ('List contacts') and the scope tag — with zero filler words. The core verb and resource are front-loaded and every token earns its place. This is appropriately sized for the tool's simplicity.

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 tool with no nested objects, the description covers the operation and the required auth scope, which is a solid baseline. But there is no output schema, and the description gives no hint about return characteristics (all contacts at once vs paginated, which fields are included), leaving the agent uncertain what the call will produce. A single clause about the result shape would round it out.

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 has zero parameters and an empty input schema, so the rubric baseline of 4 applies. There is nothing for the description to supplement; it correctly omits param detail since none exists.

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 uses a specific verb ('List') with a clear resource ('contacts'), and the 'Scope: contact:read' tag reinforces that this is the read-only listing operation, implicitly distinguishing it from the write-oriented create_contact sibling. It does not explicitly name or contrast any sibling, so it stops short of a 5, but there is no ambiguity about what the tool does.

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?

No guidance is given on when to use this tool versus alternatives. The description names no sibling, states no exclusion or alternative condition, and the only added context ('Scope: contact:read') is an auth/permission tag, not usage guidance. The agent must infer when to call it purely from the verb 'List', which is essentially restating the tool's name.

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