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

Discloses substantial server-side behavior beyond the annotations: automatic template wrapping when the 24h window is closed, the via='template' response marker, self-notification delivery behavior, and the turn-based constraint that no future work will be executed. These traits are not derivable from readOnlyHint=false, openWorldHint=true, or destructiveHint=false, and there is no contradiction with any annotation.

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?

Every sentence carries operational weight: purpose, safe case, 24h window, guardrails, and turn-based rule, with the most failure-prone rules front-loaded. The ALL-CAPS emphasis and single dense paragraph is stylistically heavy, but the length is justified by the number of critical behaviors that must be conveyed.

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, zero-required, no-output-schema tool, the description plus schema covers purpose, parameter semantics, window handling, self-notification, and the turn-based policy. The only gap is the standard response format — only the via='template' return marker is described — but this is a minor omission for a send operation.

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%, with each of the 5 parameters already richly documented (e.g., 'to' covers digit-only format and owner-omission behavior; template_name enumerates all templates with variable orders). The main description reinforces the usage context of 'to' and 'message' but adds no meaning beyond what the schema provides, so the baseline 3 applies.

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+resource: 'Sends a WhatsApp message via the Kontato bridge number.' It goes beyond the title by specifying the bridge mechanism and immediately distinguishing a key variant (self-notification when 'to' is omitted), which separates it from siblings like reply and schedule.

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 gives explicit when/when-not guidance: omit 'to' for self-notification, send just 'message' and let the server resolve the 24h window, never ask the owner to send a greeting first, and for recurring requests deliver today and direct the owner to register a schedule. It explicitly names the schedule sibling as the alternative for future/recurring work.

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