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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds that results include status and capability flags, which is useful but does not go beyond what an output schema would supply. No additional behavioral context such as pagination or filtering is provided, so a mid-range score is appropriate.

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 two short sentences with no filler. The primary action and scope are front-loaded, and the second sentence adds meaningful output context. Every word earns its place.

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, read-only list operation with one well-documented parameter, an output schema, and strong annotations, the description is sufficiently complete. Nothing critical is missing for an agent to select and 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 agentId clearly documented as 'Agent whose phone numbers to list.' The description essentially repeats the same agent scoping, adding no new meaning beyond the schema. Baseline 3 is correct when the schema already documents the parameter well.

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 and resource: 'List phone numbers assigned to an agent.' It also adds output detail (status and capability flags), making the tool's purpose unmistakable. It clearly distinguishes from siblings like phone_number_provision and phone_number_release.

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 makes the context clear: this lists phone numbers for a specific agent, so an agent can infer when to call it. However, it does not explicitly contrast with alternatives such as phone_number_provision, phone_number_release, or phone_call_list, nor does it state when not to use it.

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