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

Annotations declare read-only and non-destructive, but the description adds valuable behavioral context: the misleading nature of connected, the authoritative fields to trust, the semantics of link_state, and the warning that wacli is an unofficial client with ToS restriction risk. No contradiction with annotations.

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 earns its place: first the purpose and outputs, then the key interpretation pitfall, then the actionable consequence, then the risk warning. The link_state values are formatted as a clear list, and the description is dense without being bloated.

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 zero-parameter read-only diagnostic with an output schema, the description is fully complete: it lists the returned fields, explains their meaning, instructs how to interpret them, warns against the common connected=false misinterpretation, and flags the risk of the underlying client. Nothing essential is missing for correct invocation and interpretation.

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 accepts zero parameters, so there are no parameter semantics to clarify. With 100% schema coverage and a direct focus on output interpretation, the description fully compensates for the absence of parameters.

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: 'WhatsApp health check (wacli doctor)', and enumerates the exact outputs (account number, sync time, store lock, counts, link_state verdict, sync fields). This clearly distinguishes the diagnostic tool from write/link tools like whatsapp_connect and whatsapp_sync.

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?

Provides strong contextual guidance: 'Read link_state and requires_user_action, NOT connected', explains why connected is unreliable, and gives state-specific interpretations (not_linked → scan QR, linked_idle → nothing to do). It mentions the background job started by whatsapp_sync but does not explicitly name the alternative tool for linking or syncing, so it falls just short of fully explicit alternative routing.

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