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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the mutation profile is covered. The description adds the 5MB cap and the JPEG/PNG constraint plus the public-https requirement, which is useful, but says nothing about permissions, reversibility of the replaced photo, or failure behavior.

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?

Two short sentences, action front-loaded, with the alternative input modes and hard limits packed in without waste. Every clause 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 5-parameter mutation with no output schema and full schema coverage, the description supplies the key constraints an agent needs to call it correctly. What remains uncovered — id semantics for profile_id/phone_number_id — is handled by the schema descriptions.

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%, so the baseline is 3, and the description goes beyond it by stating the url/data mutual exclusivity and tying content_type to the data path — conditions the schema does not express. It does not document profile_id or phone_number_id semantics, so not a 5.

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 and resource ('Replace the profile photo of a phone number'), which is clearly distinct from the general sibling whatsapp_business_profile_update and the display-name tools. It does not explicitly name the sibling it differs from, so it falls short of a 5.

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 tells the agent how to supply the image (url vs data) but gives no guidance on when this tool should be used instead of whatsapp_business_profile_update. Usage is implied by the narrow scope rather than stated.

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