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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so 'Read-only' is partly redundant but consistent. Beyond the annotations, the description discloses meaningful behavior: results are in priority order and each item carries 4-character IDs, schedules, warm/cold mode and active state – return-shape information the agent would otherwise lack.

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 dense sentence front-loads the resource and scope, then enumerates returned fields, ending with the safety qualifier. No filler or repetition.

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?

No output schema exists, and the description compensates by enumerating the returned fields (IDs, schedules, mode, active state) and ordering. Combined with full parameter coverage and rich annotations, an agent has everything needed to call and interpret this tool.

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?

One parameter with 100% schema description coverage ('Receptionist ID from listAgents'), so the schema already explains both meaning and provenance. The description adds nothing about the agentId, which is acceptable given full coverage; baseline 3 applies.

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+resource ('List a receptionist's transfer numbers') and even disambiguates the domain concept with a parenthetical explanation of what transfer numbers are (handoff points for live calls). The name plus description make it unambiguous against siblings like transfer_numbers_add or transfer_numbers_reorder.

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?

Usage is only implied: the description says it lists existing numbers and is read-only, which hints at inspection-before-mutation workflows, but it never explicitly contrasts with transfer_numbers_update or transfer_numbers_add, nor states prerequisites. Adequate but with clear gaps.

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