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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds nothing beyond that: it does not say whether the code is returned in the response or dispatched to the phone, whether it expires, or whether requesting it has an outward-facing effect (e.g. sending an SMS/WhatsApp message) that the readOnly framing might lead an agent to underestimate.

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 short sentence with no filler, and the resource being fetched is front-loaded. It is efficient but arguably under-written given the ambiguity it leaves, so it stops short of a 5.

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?

A two-parameter read tool with full schema coverage and annotations is close to self-describing, but the critical ambiguity remains unresolved: whether the authorization code comes back in the response or arrives on the phone, and whether the instance must already exist/be paired. With no output schema, the description should have closed that gap.

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 coverage is 100% and the schema documents both parameters including a phone-number format example, so the description needn't restate them. It adds no meaning beyond the schema — the phrase "by phone number" merely echoes the phone_number property.

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 pairs a specific verb ("Get") with a specific resource ("authorization code for sign-in") and adds the scoping qualifier "by phone number." That is enough to know what the tool returns, but nothing distinguishes it from near neighbours such as whatsapp_get_qr or whatsapp_check_whatsapp, which are also part of the sign-in/connection flow.

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?

There is no statement of when to call this instead of whatsapp_get_qr, whatsapp_check_whatsapp, or whatsapp_connect, nor any prerequisite such as the instance needing to be connected first. The agent must infer the sequencing of the auth flow entirely from the sibling names.

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