wa_list_accountsList the WhatsApp accounts available to you. Call this first: every other wa_ tool needs an account_id from here. An account is only usable while its state is "connected" (status "live"); otherwise status and what_to_do say why and what to do.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| accounts | Yes | the WhatsApp accounts this API key can use |
Changes observed during successful MCP inspections.
Output schema / properties / accounts / items / properties / statusAdded value: +{
+ "description": "whether the number is actually working: live, connecting, starting, not_running, whatsapp_down, suspended, pairing, unlinked or locked",
+ "type": "string"
+}Output schema / properties / accounts / items / properties / status_reasonAdded value: +{
+ "description": "the detail when it is not live, e.g. no_egress, no_plan, stopped",
+ "type": "string"
+}Output schema / properties / accounts / items / properties / status_sinceAdded value: +{
+ "description": "when it stopped working, RFC3339, when known",
+ "type": "string"
+}Output schema / properties / accounts / items / properties / what_to_doAdded value: +{
+ "description": "what is wrong and what to do, when it is not live; tell the user",
+ "type": "string"
+}Output schema / properties / accounts / items / properties / backendAdded value: +{
+ "description": "the account's backend: official (WhatsApp Business API) or personal (a linked device)",
+ "type": "string"
+}Output schema / properties / accounts / items / properties / featuresAdded value: +{
+ "description": "the functions this number supports, e.g. messaging, templates, groups, calls; call only tools whose function is listed here",
+ "items": {
+ "type": "string"
+ },
+ "type": [
+ "null",
+ "array"
+ ]
+}Output schema / properties / accounts / items / requiredPrevious value: -[
- "account_id",
- "phone",
- "push_name",
- "state"
-]New value: +[
+ "account_id",
+ "phone",
+ "push_name",
+ "state",
+ "backend",
+ "features"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds real behavioral context beyond that: an account is only usable when state is 'connected' (status 'live'), and otherwise status/what_to_do explain the failure. It does not address the idempotentHint=false flag, leaving a small gap.
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?
Three short sentences, each earning its place: what it does, when to call it, and how to interpret the result. The critical prerequisite is front-loaded rather than buried.
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?
An output schema exists, so return values need not be enumerated, yet the description still explains how to read the key fields (state/status/what_to_do). Prerequisite, usability condition, and failure interpretation are all present for a zero-parameter listing tool.
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?
The tool takes zero parameters, so the baseline is 4; there is nothing for the description to disambiguate. The schema is closed (additionalProperties: false), so no risk of an agent inventing inputs.
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+resource ('List the WhatsApp accounts') and immediately distinguishes itself from siblings like wa_pair_account and wa_pair_status by establishing it as the entry point. An agent can identify its role without opening the 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?
Explicitly states when to use it ('Call this first') and why ('every other wa_ tool needs an account_id from here'), which is a concrete ordering prerequisite rather than vague guidance. It also gives the precondition for acting on a result (state 'connected').
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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