Account and phone numbers

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

Annotations declare readOnlyHint=true and openWorldHint=true, so safety is covered structurally. The description adds genuine behavioral context beyond them by specifying what capabilities are reported per number (sending, and the initiate-vs-reply-only distinction), which is the key operational fact an agent needs. It does not mention auth scope or workspace multiplicity, but with annotations present the bar is lower.

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 sentence, front-loaded with the resource and then the three facts returned. The colon-and-clause chain ('which number is which, whether each can send, and whether...') is slightly list-like but every clause carries information. No filler.

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?

With no parameters and no output schema, the description carries the burden of describing the return value, and it does so at the right level: identity, send eligibility, and conversation-initiation capability. It could say more about shape (e.g., how numbers are identified), but for a simple account getter this is close to complete.

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 takes zero parameters, so there are no semantics to explain and the baseline is 4. The description wastes no space inventing parameter detail.

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 title and description name the resource (the Blujay workspace and its phone numbers) and enumerate the specific facts returned: number identity, send capability, and whether a number can initiate conversations or only reply. The verb is implicit (a zero-argument getter), but the resource and payload are concrete enough to separate it from message-oriented siblings like get_conversation or send_message.

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: an agent can infer it should call this to learn which number to send from, or whether a number may start a conversation. No explicit when-to-use framing, prerequisites, or named alternatives appear. Nothing is misleading, but the routing guidance is left to inference.

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