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

With annotations covering the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), the description still adds meaningful behavior: custom templates return PENDING, library templates are approved instantly, and a named webhook (message_template.status_updated) plus a re-list-with-refresh path are offered for tracking. It stops short of noting auth/permission requirements or rate limits.

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?

Roughly four dense sentences, front-loaded with the core action before the two-branch detail and the async outcome. No filler, though the middle sentence packs several constraints (name charset, category enum) that the schema already encodes and could be trimmed.

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 10-parameter mutation tool with no output schema, the description covers both invocation branches and what happens after submission (PENDING vs instant approval, webhook vs refresh). It does not state what the response object contains (e.g., template id), but the state-change information an agent needs to proceed is present.

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 90% so the baseline is 3, but the description adds real semantics: it maps 'components' to Meta's HEADER/BODY/FOOTER/BUTTONS shape and stresses that example values are required for any {{n}} placeholders, and it explains that library_template_name/body/button inputs are the alternative path. It does not restate the TTL or parameter_format details, which the schema already covers.

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 opens with a specific verb and resource: 'Submit a new WhatsApp message template to Meta for review.' It clearly separates this tool from siblings like whatsapp_template_update (modify), whatsapp_template_delete, and whatsapp_template_library_get (browse), so an agent can pick the right one without opening schemas.

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?

It gives explicit routing between the two creation modes: pass 'components' for a custom template or 'library_template_name' to instantiate a pre-approved one, and points to whatsapp_template_library_get for the library entry name. It does not explicitly say what to do for modifying an existing template (use whatsapp_template_update instead), which is the main remaining gap.

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