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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds real value beyond that by spelling out the returned attribute set and noting the platform_type distinction (CLOUD_API vs a coexistence number still in the WhatsApp Business app), which tells the agent what it will actually get back. It stops short of mentioning latency, caching, or auth requirements.

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 front-loaded sentence that leads with the verb and resource, then enumerates the payload. Nothing is redundant, and every listed field earns its place because no output schema exists to carry that information.

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 output schema, the description correctly compensates by enumerating the returned fields, and the annotations cover the safety profile. Both required parameters are fully described in the schema, so an agent has everything needed to call this 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% and both required parameters (profile_id, phone_number_id) are documented in the schema itself. The description adds no additional meaning about either parameter, so the baseline 3 is appropriate when the schema does the heavy lifting.

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 ('Read') and resource ('live state of a WhatsApp phone number from Meta') and then enumerates the exact fields returned (quality_rating, messaging_limit_tier, throughput, platform_type, review/verification status). This field set lets an agent distinguish it from look-alike siblings such as whatsapp_display_name_get, whatsapp_username_get, and whatsapp_business_profile_get without opening a schema.

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 implied by 'Read the live state of a WhatsApp phone number' — an agent can infer this is the tool for inspecting a number's current Meta-side attributes. However, there is no explicit when-to-use, when-not-to-use, or named alternative (e.g. vs whatsapp_display_name_get or whatsapp_business_profile_get), so routing 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.